Blood cells“Blood cell”It is a cell existing in the blood and can spread all over the body with the flow of blood.withmammalFor example, blood cells mainly include the following three types:red blood cell: The main function is to transportoxygen。white blood cell: It mainly plays the role of immunity.When germs invade the human body, white blood cells can pass throughCapillary wall, concentrate on the invasion site of bacteria, surround the bacteria and swallow them.Platelets: play an important role in hemostasis.Blood cells account for aboutvolume45%, including red blood cells, white blood cells and platelets.Under normal physiological conditions, blood cells and platelets have a certain morphological structure and a relatively stable number.[1]
Hematopoietic cells derived from bone marrowPluripotent stem cell。In addition to the ability to proliferate, stem cells can migrate out of bone marrow hematopoietic tissue under certain conditions, and form hematopoietic cell nodules, called colony forming units, when they reach extramedullary tissue with blood flow.Each summary is composed of many differentiated cells of the same type, which are derived from the division and differentiation of a stem cell.Although stem cells have the ability to replicate and differentiate themselves into various blood cells, in general, they are not in the state of proliferation, but in the resting G0 phase.
Primitive stem cells can differentiate into two branches: one is colony forming unit cells (CFU-C), also known asBone marrow stem cellsIt is red blood cell, neutrophilEosinophilsAnd platelets.Colony forming unit cells mainly come from bone marrow. Before they develop into red blood cells, granulocytes and megakaryocytes, they must go through the stage of directional stem cells of various lines.The other isLymphoid stem cells, also known as lymphoid stem cellsAnimal immune systemIts differentiation and development are closely related to the stimulation of antigen, and lymphoid stem cells are alsoPluripotent stem cell, can differentiate into two different kinds of directional stem cells. One is thymus derivedT lymphocytesOr T cell, one is bone marrow dependentB lymphocytesB cells, or B cells, are transformed into prolymphoblastic cells and protoplasmic cells by the stimulation of corresponding antigens, and then gradually mature, called lymphocytes and plasma cells, respectively.
In a word, blood cells are hematopoietic pluripotent stem cells derived from bone marrow. First, pluripotent stem cells differentiate into colony forming unit cells (bone marrow stem cells) and lymphoid stem cells, and then bone marrow stem cells differentiate into directional stem cells of various lines. After primitive and immature stages, development and proliferation finally mature into red blood cells, granulocytes, monocytes and platelets.Lymphoid stem cells, on the other hand, undergo two stages of primordial and infantile development, proliferation and maturation;Under the stimulation of antigen, they will be transformed into prolymphoblasts and protoplasm cells, and proliferate and mature into lymphocytes and plasma cells with immune activity.
The proliferation of blood cells is carried out by way of division, but only immature cells have the ability to divide. Once the development reaches a certain stage, the proliferation stops.Generally, there are two forms of cell division:
(1) Mitosis (indirect division) is called mitosis because special mitoses appear during cell division.mitosisIt is the main form of blood cell proliferation.There are no mitotic cells in the circulating blood of normal people.Mitotic cells
The quantity in hematopoietic tissue reflects the degree and state of its proliferation.The process of division can be divided into four stages, mainly manifested in nuclear changes. ①Prophase (also known as monofilament stage): when the cell begins to divide, the cell body becomes spherical and the nucleus expands,Nuclear chromatinAggregation
The single columnar chromosome, nuclear membrane and nucleosome disappeared, like a silk ball.Cytoplasmic staining becomes shallow, and organelles and inclusions are temporarily hidden,CentrosomeDisplay. ②Mid stage (also known as single star stage): the centrosome begins to split and gradually moves towardsBipolar, connected with filaments
The body, shaped like a spindle, is called a spindle.The nuclear chromosomes are arranged in the middle of the spindle, like stars or chrysanthemums. ③Anaphase (also called double star stage): each chromosome splits into two evenly, and the filamentous body shrinks, so that the chromosome after division tends to two cells with the centrosome
End, respectively arranged into two stars.The cytoplasm began to shrink. ④Late stage (also calledFilamentary stage）: Chromosomes tending to both ends of the cell begin to gather into silk balls, and then disperse intoChromatin, the small nucleus that forms two new nuclei, and the cytoplasm can form dumbbells
Finally, the cytoplasm separates and the cell divides into two.
(2) Amitosis（Direct fission）The expression form of this division process is relatively simple. Generally, the nucleosome of the cell starts to separate first, then the surface of the cell nucleus shrinks, and then gradually deepens and decomposes into two, followed by the separation of the cytoplasm, thus directly forming two daughter cells.
Main types
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red blood cell
red blood cell
The diameter of red blood cell (RBC) is 6-9.5 μ m, with an average of 7.2 μ m, which is in the shape of double concave disc, and the center is thin (1.0 μ m),PeripheryIt is thicker (2.0 μ m), soBlood smearIn the specimen, the central staining is shallow, the periphery is deep, and there is no nucleus.stayscanning electron microscopeThe morphological characteristics of red blood cells can be clearly shown.This shape of red blood cell makes it have largerSurface area(about 140 μ m2), so as to adapt to its function - carrying O2 to the maximum extent.The fresh single red blood cell is yellow green, and a large number of red blood cells make the blood scarlet, and many red blood cells are often stacked together in a string of money, calledRed blood cell roulea line。Mature red blood cells have no nuclei, and their shape is like a round cake with concave centers on both sides.
Red blood cells have certain elasticity and plasticity, and can change shape when passing through capillaries.The maintenance of the normal morphology of red blood cells requires ATP to supply energy, due to the lack of red blood cellsmitochondrionATP is produced by anaerobic fermentation;However, the lack of ATP energy supply will lead to the change of cell membrane structure, and the shape of cells will also change from disk to spine ball.This morphological change is generally reversible.It can be recovered with the improvement of ATP energy supply status.
Mature red blood cells have neither nuclei nor organelles, and their cytoplasm is full of hemoglobin (Hb).hemoglobinIt is an iron containing protein, accounting for about 33% of the weight of red blood cells.It has combination and transportation OtwoAnd COtwoWhen the blood flows through the lungs, the OtwoPartial pressure high, COtwoWhen the partial pressure is low, hemoglobin will release COtwoAnd with Otwocombination;When blood flows through tissues of other organstwoPartial pressure is high while OtwoWhen the partial pressure is low, the red blood cell will release OtwoCombined with COtwo。Because hemoglobin has this property, red blood cells can supply O needed by tissues and cells of the whole bodytwoTake away part of CO generatedtwo。
The average number of red blood cells per microliter of blood in normal adults is about 4 million to 5 million for males and 3.5 million to 4.5 million for females.The hemoglobin content in every 100ml of blood is about 12-15g for men and 10.5-13.5g for women.The total surface area of all red blood cells in the whole body is 2000 times that of the human body.There may be physiological changes in the number of red blood cells and the content of hemoglobin. For example, infants are higher than adults, more than in the quiet state when exercising, most residents in plateau areas are higher than those in plain areas, and changes in the shape and number of red blood cells, as well as changes in the quality and quantity of hemoglobin are beyond the normal range, which is a pathological phenomenon.Generally speaking, anemia occurs when the number of red blood cells is less than 3 million/μ 1 and the hemoglobin is less than 10 g/100ml.At this time, it is often accompanied by changes in the diameter and morphology of red blood cells. For example, the average diameter of red blood cells in megaloblastic anemia is more than 9 μ m,Small red blood cellThe average diameter of red blood cells in anemia is less than 6 μ m.iron-deficiency anemiaBecause the hemoglobin content in the red blood cells of.
The osmotic pressure of red blood cells is equal to that of plasma, so as to maintain the balance of water in and out of red blood cells.WhenPlasma osmolalityWhen it decreases, excess water enters the cell, the cell expands into a ball, or even breaks, and hemoglobin escapes, which is calledhemolysis（hemolysis）；Residual after hemolysisErythrocyte membraneThe sac is calledBlood shadow（ghost）。On the contrary, if the osmotic pressure of plasma is increased, too much water in red blood cells can be analyzed, which will cause red blood cells to shrink.Factors that can damage red blood cells, such asLipoid solvent、snake venom、Hemolytic bacteriaCan cause hemolysis.
The cell membrane of red blood cells, in addition to the commonness of general cell membranes, also has its particularity. For example, there areABO blood group antigen。
Peripheral bloodIn addition to a large number of mature red blood cells, there are a small number of immature red blood cells, calledReticulocyte(reticulocyte) is about 0.5%~1.5% of the total number of red blood cells in adults and 3%~6% in newborns.The diameter of reticulocytes is slightly larger than that of mature red blood cells, and they cannot be distinguished from mature red blood cells in routine blood smears.Use brilliant burnt blue as external bodyLiving stainingIt can be seen that there are blue fine nets or particles in the cytoplasm of reticulocyte, which are residual in the cellribosome。The presence of ribosomes indicates that reticulocytes still have some functions of hemoglobin synthesis.When the red blood cells are fully mature, the ribosome disappears and the hemoglobin content no longer increases.If the hemopoietic function of anemia patients is good, the percentage of reticulocytes in their blood will increase.Therefore, the count of reticulocytes has certain clinical significance. It is due to anemia, etcHematopathyIt is one of the predictors of diagnosis, curative effect judgment and estimation.
The average life span of red blood cells is about 120 days.Although senescent red blood cells have no morphological specificity, their functional activities and physical and chemical properties have changed, such as decreased enzyme activity, hemoglobin degeneration, increased membrane fragility, andsurface charge As a result, the ability of cells to combine with oxygen is reduced and easily broken.Senile red blood cells are mostly covered in the spleen, bone marrow and livermacrophageEngulfed byRed bone marrowThe production and release of the same number of red blood cells into the peripheral blood to maintain a relatively constant number of red blood cells.[1]
white blood cell
1. Concept and classification
Red blood cell (RBC) and white blood cell (WBC)
white blood cell(Leukocyte, white blood cell) is colorless with coreSpheroid cellIt is larger than red blood cells in volume, can make deformation movement, and has defensive and immune functions.The normal value of adult leukocytes is 4000~10000/μ 1.There is no significant difference between men and women.Infants are slightly higher than adults.The number of white blood cells in the blood can be affected by various physiological factors, such as labor, exercise, diet and women's menstrual period, which are slightly increased.In the state of disease, the total number of white blood cells and the percentage value of various white blood cells can change.Under light microscope, according to whether there are special particles in the cytoplasm of white blood cells, they can be divided into two categories: granulocytic white blood cells and non granulocytic white blood cells.Granular leukocytes can be divided intoNeutrophils, eosinophils andBasophil。No granulocyte YesmonocyteandlymphocyteTwo.
2. Neutrophil
neutralGranulocyte(neutrophil granulocyte, neutrophil) accounts for 50% - 70% of the total number of white blood cells, which is the largest type of white blood cells.The cells are spherical, 10-12 μ m in diameter, and the nuclear chromatin is lumpy.The shape of the nucleus is diverse, some of which are sausage shaped, called rod-shaped nucleus;Some are lobulated, with filaments connecting between the leaves, called lobulated nucleus.The nucleus is generally 2-5 lobes, and 2-3 lobes are the majority in normal people.In some diseases, the percentage of cells in the 1~2 lobes of the nucleus increases, which is called nuclear left shift;The number of cells in 4~5 lobes of nucleus increases, which is called nuclear right shift.Generally speaking, the more nuclear lobulation, the more senescent cells are, but this is not absolute. In some diseases, new neutrophils can also have nuclei with 5 or more lobes.The rod-shaped nuclear granulocytes are relatively immature, accounting for 5%~10% of the total number of granulocytes. When the body is seriously infected by bacteria, the proportion is significantly increased.
The cytoplasm of neutrophils is dyed pink and contains many small lavender and reddish particles. The particles can be divided intoTianqing GranulesAnd special particles.There are few azurophile particles, which are purple, accounting for about 20% of the total particles. Under the light microscope, they are slightly darker and larger;Electron microscopeIt is round or oval at the bottom, with a diameter of 0.6 ～ 0.7 μ m,electron densityHigher, it is a kind oflysosome, containingacid phosphataseandPeroxidaseIt can digest, decompose and swallow foreign matters.The number of special particles is large, light red, accounting for about 80% of the total number of particles. The particles are small, 0.3~0.4 μ m in diameter, dumbbell shaped or oval, containingalkaline phosphatase, PhagocytosinlysozymeEtc.Phagocytosin has bactericidal effect and lysozyme can dissolveglycoprotein。
Neutrophils have active deformation movement and phagocytic function.When a certain part of the body is invaded by bacteria, neutrophils have chemotaxis to bacterial products and some chemical substances released by infected tissues. They can penetrate capillaries through deformation movement, gather to the site of bacterial invasion, swallow a large number of bacteria, and form phagosomes.The phagosomes fuse with special particles and lysosomes successively, and the bacteria are then exposed to various hydrolasesoxidaseLysozyme and other bactericidal proteinspolypeptideAnd other ingredients to kill, decompose and digest.It can be seen that neutrophils play an important defensive role in the body.NeutrophilsPhagocyteLater, it often necroses and becomesPurulent cell。Neutrophils stay in the blood for about 6-7 hours and survive in the tissues for about 1-3 days.
3. Eosinophils
Eosinophil granulocyte (eosinophil) accounts for 0.5% - 3% of the total number of leukocytes.The cells are spherical, with a diameter of 10-15 μ m, and the nucleus is usually two leaves. The cytoplasm is full of large, uniform, slightly refractive eosinophilic particles, which are dyed orange red.Under the electron microscope, the particles are mostly oval, with membrane coating, containing granular matrix and square or rectangular crystals.The particles contain acid phosphataseAryl sulfatase, peroxidase and histamine enzyme, so it is also a lysosome.
Eosinophils can also deform and have chemotaxis.It can swallowantigenAntibody complex, which releases histamine enzyme to inactivate histamine, thereby weakening allergic reaction.Eosinophils can also use antibodies toparasiteThe surface combines to release substances in particles and kill parasites.Therefore, eosinophils have anti allergic and anti parasitic effects.In allergic diseases or parasitic diseases, eosinophils in the blood increase.It usually stays in the blood for only a few hours and can survive in the tissues for 8-12 days.
4. Basophil
The number of basophilic granulocyte (basophil) is the smallest, accounting for 0%~1% of the total number of white blood cells.The cells were spherical and 10-12 μ m in diameter.The nuclei are lobulated or S-shaped or irregular, with light staining.The cytoplasm contains basophilic particles with different sizes and uneven distribution, which are dyed blue purple and can cover the nucleus.The particles haveHeterochromaticity，toluidine blueIt is dyed purple red.Under the electron microscope, the basophilic particles are filled with fine particles, which are distributed in a uniform or threadlike manner.The particles containheparinAnd histamine, which can be rapidly released;Leukotriene exists inCell matrixIts release is slower than the former.Heparin has antiCoagulationHistamine and leukotriene are involved in allergic reaction.Basophils can survive for 12-15 days in tissues.
Basophils andmast cellsThey are different in distribution, shape of nucleus, size and structure of particles.But both cells contain heparinhistamineThe function of basophils is similar to that of mast cells, but the relationship between basophils and mast cells remains to be studied.
5. Monocyte
Monocytes account for 3%~8% of the total number of white blood cells.It is the largest white blood cell.The diameter is 14-20 μ m, round or oval.The nuclei have various shapes, such as oval, kidney, horseshoe or irregular.The nuclei are often offset, and the chromatin particles are fine and loose, so the staining is shallow.More cytoplasm, weakBasophilIt contains many small azurophile particles, which make the cytoplasm stained with uneven gray blue.The granules contain peroxidase, acid phosphatase, non-specific esterase and lysozyme. These enzymes are not only related to the function of monocytes, but also can be used as identification points with lymphocytes.Under electron microscope,cell surfaceThere are wrinkles and microvilli, and many phagocytes, mitochondria andRough endoplasmic reticulumThe particles have lysosome like structure.
Monocytes have active deformation movement, obvious chemotaxis and certain phagocytic function.Monocyte is the predecessor of macrophage. It stays in the blood stream for 1-5 days, passes through the blood vessel, enters the tissue andCoelom, differentiated into macrophages.Both monocytes and macrophages can eliminate bacteria invading the body, swallow foreign particles, eliminate cells damaged by aging in the body, and participate in immunity, but their functions are not as strong as macrophages.
6. Lymphocytes
Lymphocytes account for 20%~30% of the total number of white blood cells. They are round or oval in size.Small lymphocytes with a diameter of 6-8 μ m and 9-12 μ mMesolymphocyte13 ～ 20 μ mLarge lymphocyte。The number of small lymphocytes is the largest, the nucleus is round, and there are often small depressions on one side. The chromatin is dense and massive, with deep coloring. The nucleus accounts for most of the cells, and the cytoplasm is few. It forms a narrow margin around the nucleus, basophilic, dyed blue, containing a small amount of azurophilic particles.The nucleus of middle and large lymphocytes is oval, and the chromatin is loose, so the staining is shallow, the cytoplasm is more, and a small amount of azurophile particles can also be seen in the cytoplasm.A few large and medium lymphocytes have kidney shaped nuclei, and the cytoplasm contains more large astrophilic particles, which are calledLarge granular lymphocyteUnder electron microscope, the cytoplasm of lymphocytes is mainly largeFree ribosomeOther organelles are underdeveloped.
It was previously believed that the differentiation degree of large, medium and small lymphocytes was different, and small lymphocytes were terminal cells.However, it is generally believed that most small lymphocytes are not terminal cells.Under the stimulation of antigen, it can transform into immature lymphocytes, and then proliferate and differentiate.Moreover, lymphocytes are not a single group. According to their location, surface characteristics, life span and immune function, they can at least be divided into T cellsB cell, killer (K) cells and natural killer (NK) cells.
T cells in the blood account for about 75% of the total number of lymphocytes, and they participate incellular immunity, such as rejection of allografts, anti-tumor, etc., andImmunomodulationFunction.B cells account for 10%~15% of the total number of lymphocytes in the blood.B cells proliferate and differentiate intoplasma cells, produce antibodies, participate inhumoral immunity。
platelet
platelet
Blood platelets are exfoliations of the cytoplasm of bone marrow megakaryocytes, not cells themselves.The normal value is 100000~300000/μ 1.It is in the bone marrowMegakaryocyteThe small pieces of cytoplasm fall off, so there is no nucleus, and there is a complete cell membrane on the surface.Platelets are small in size, 2-4 μ m in diameter, and double convex and flat plates;When subjected to mechanical or chemical stimulation, the protrusions are irregular.In blood smears, platelets are often polygonal and clustered.There are blue and purple particles in the central part of the platelet, called granulomere;The periphery is homogeneous light blue, called hyalomere.Under the electron microscope, the membrane surface of the platelet has a sugar coating, and the cell has no nucleus, but there are tubules, mitochondria, microfilaments andmicrotubuleAnd platelet granules and glycogen granules.
Platelets play an important role in hemostasis and coagulation.The surface sugar coating of platelets can adsorbPlasma proteinandCoagulation factorⅢ. Platelet particles contain substances related to coagulation.When the blood vessel is damaged or ruptured, the platelet is stimulated and changes from a static phase to a functional phase, which immediately deforms, increases the surface viscosity, and agglomerates into a group;At the same time, under the action of surface factor IIIthrombinTo thrombin, which catalyzesFibrinogenFilamentousfibrin, forming clots with blood cells to stop bleeding.plateletParticulate matterAnd further promote hemostasis and coagulation.Platelets also protect vascular endothelium, participate in endothelial repair, and preventatherosclerosisRole of.The life span of platelets is about 7-14 days.When the number of platelets in the blood is less than 100000/μ 1ThrombocytopeniaIf it is less than 50000/μ 1, there is a risk of bleeding.
There are two kinds of platelet granules: special granules and dense granules.Special particles, also called α particles, are large and round,electron densityMedium, containing coagulation factor IIIacid hydrolaseEtc.Small dense particles, high electron density, containing 5-hydroxyTryptamine、ADP、ATP、calcium ion、adrenalineEtc.The release of the contents of both particles is related to platelet function.There are also two types of platelet tubules: open tubules and dense tubules.Open tubules are scattered, with bright lumens, which open on the surface of platelets to absorb plasma substances and release particulate contents.Dense tubules are closed tubules, mostly distributed around platelets, with medium electron density in the lumen, which can collect calcium ions and synthesizeprostaglandinEtc.There is circular arrangement around plateletsMicrofilamentAnd microtubules, related to the morphological changes of platelets.
anemia
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Mature red blood cells have neither nucleus norOrganelleThe cytoplasm is full of hemoglobin.
Hemoglobin is an iron containing protein, accounting for 33% of the weight of red blood cells.It has combination and transportation OtwoAnd COtwoWhen the blood flows through the lungs, the OtwoPartial pressure high, COtwoWhen the partial pressure is low, hemoglobin will release COtwoAnd with Otwocombination;When blood flows through tissues of other organstwoPartial pressure is high while OtwoWhen the partial pressure is low, the red blood cell will release OtwoCombined with COtwo。Because hemoglobin has this property, red blood cells can supply O needed by tissues and cells of the whole bodytwoTake away part of CO generatedtwo。In short, blood cells are used to transport OtwoIf the number of blood cells decreases, the number of red blood cells will decrease and anemia will occur.
Specific volume
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1. The percentage of blood cells in the whole bloodvolumePercentage, scaleHematocrit。
2. English name: chemocrit Abbreviation:Hematocrit；Red blood cell ratio of body parts or organs: automatic blood cell analyzer:
Male: 0.40~0.50 (40~50vol%);
Female: 0.37~0.48 (37~48 vol%);
Newborn: 0.49~0.60 (49~60 vol%).
Significance of examination results: (1) increase: ① severe dehydration (massive vomiting, diarrhea, dehydration, etc.)Large area burn. ③Polycythemia vera。④Secondary polycythemia(Newborn, plateau disease, severePulmonary heart diseaseEtc.).(2) Decrease: ① anemia or pregnancy hypoxemia. ②secondaryFibrinolysisSymptoms. ③epidemic hemorrhagic feverComplicated with hypervolemic syndrome. ④Pregnancy induced hypertension.
Hematocrit is helpful to understand the increase and decrease of red blood cells. When the absolute value of red blood cells increases due to various reasons, the hematocrit will also increase accordingly.
Reference value: male: 0.40-0.50L/L (40-50%);
Female: 0.37-0.45L/L (37% - 45%).
After anticoagulation treatment, the blood can be divided into two parts by centrifugation, plasma and blood cells.If the blood is placed in a special test tube (Winchester tube) and centrifuged at the specified time and speed, the red blood cells will finally be completely compacted at the bottom of the test tube. The red blood cells will contact each other closely, and all plasma will be eliminated as far as possible. At this time, the plasma will be squeezed out onto the blood cells,At this time, the percentage of red blood cells in the whole blood is the hematocrit we need to get, that is, the volume (or percentage) of compacted red blood cells, also calledHematocritOr hematocrit.Hematocrit can also be measured by capillary method and blood cell counter method.Hematocrit is usually abbreviated as HCT or Ht, and the measurement unit now uses the number of liters occupied by red blood cells per liter of blood to express (L/L).
The determination of hematocrit is helpful to understand the increase and decrease of red blood cells. When the absolute value of red blood cells increases due to various reasons, hematocrit will also increase accordingly.When blood is concentrated, hematocrit can reach more than 50%. It is often used clinically to understand the degree of blood concentration of dehydration patients as a reference for calculating the amount of fluid replacement.The decrease of hematocrit is lower than that of various anaemia. Due to the different volume of red blood cells, the change of hematocrit is not parallel to the number of red blood cells. The number of red blood cells andHemoglobin concentrationAnd used to calculate the average values of red blood cells.
Blood cell analyzer
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Instrument Introduction
Since the early 1950sKurtMr. Li invented the patent of particle counting technology and produced the firstHematology analysisSince the instrument was used in clinic,Blood cell analyzerIt has a history of 50 years. Hematology analyzer essentially refers to an instrument that analyzes the number and heterogeneity of blood cells in a certain volume. The original cell counter can only count red cells (RED) and white blood cells (WBC). Later, there were red egg white (HBG), platelets (PLT), and hematocrit (HCT),Mean corpuscular volume(MCV), etc.After the development of Hematology Analyzer, many analysis and calculation parameters have been added, such asRed blood cell volume distribution width(RDW),Mean platelet volume(MPV), platelet volume distribution width (PDW), platelet hematocrit (PCT),Large platelet ratio, three groups of white blood cells, five groups of white blood cells, distribution width of hemoglobin concentration, indication of abnormal lymphocytes,Immature cellPrompts and other parameters and functions are constantly added to some brands of instruments.
The basic principle of the resistance detection method is: place a micro hole in the liquid to be measured, and apply a certain voltage electrode at both ends of the micro hole. When the particles in the liquid pass through the micro hole, the resistance between the electrodes will change instantaneously, so as to generate electric pulse. The number of particles can be obtained by counting the electric pulse,The size of the pulse amplitude represents the size of the particle volume, and different types of cells can be distinguished by selecting the size of the electrons generated by the pulse of various cells;Adding a certain negative pressure to the liquid can make the liquid flowing through the micropores.
With electronic technology,Flow cytometryThe application of laser technology, electronic computer technology, new fluorescent chemicals and other high-tech technologies in clinical laboratory work has improved the blood cell analyzer to a new stage in terms of automation, advanced functions and perfect design. The blood cell analyzer has not only been limited to routine blood cell analysis, but also added many expanded functions,For example, the counting and analysis function of reticulocyte (RET) is added, and some instruments also add the analysis of immature cells andNucleated red blood cellThe analysis function even prompts some parasites in the blood cells. Some instruments combine some functions of the flow cytometer with the blood cell analyzer to get some information when performing routine blood cell analysisLymphocyte subsetsAnalysis results of.
On the conventional blood cell counter, red blood cells (RBC) and platelets (PLT) share a measurement channel. The measurement principle of hemoglobin content (HGB) is the same in any type and grade of instrument.There are special channels for counting and classifying white blood cells. Now we will briefly introduce the technical methods and principles used in each test item on the analyzer.
Determination of hemoglobin content
Hemoglobin content is measured by adding hemolytic agent into the diluted blood to make the red blood cells release hemoglobin, which combines with the hemolytic agent to form hemoglobin derivatives, enters the hemoglobin test system, compares colors at a specific wavelength (generally 530-550nm), and changes in absorbance are proportional to the Hb content in the liquid,The instrument can display the concentration of Hb. Different series of blood analyzers have different hemolytic formulations, and the hemoglobin derivatives formed are also different, but most of the maximum absorption spectra are close to 540nm. In recent years, many high-end analyzers have used laser scattering method to analyze the hemoglobin of individual red blood cells, so as to minimize high WBC, chyle blood, highbilirubinAnd other effects on HBG colorimetry.
The red blood cell test isBlood analyzerIt is an important part of red blood cell detection. In the past, the impedance method was mainly used to count the number and volume of red blood cells, so as to select signals of different sizes and print out the red blood cell volume distribution histogram. But now, the combination of optical and electrical impedance methods is also used to process the red blood cell volumethree-dimensional spaceAnalyze (3D) to get more correct results. For example, Bayer's ADVIA 120 detects red blood cells with light scattering method, and uses low angle forward light scattering and high angle scatteringmeasurement system At the same time, one red blood cell was measured, and the volume and total number of single red blood cell were measured according to the size of low angle light conversion energy;Single hemoglobin concentration can be obtained according to high angle light scattering, and MCV (average red blood cell volume), MCH (average hemoglobin content), MCHC can be accurately obtained（Mean hemoglobin concentration）The measured value, red blood cell scatter diagram, histogram of single red blood cell volume and Hb content in red blood cell, RWD (red blood cell volume distribution width), HDW (red blood cell hemoglobin distribution width) and other parameters are drawn.
Due to the obvious difference in the volume of platelets and red blood cells, it is easy to distinguish the photoelectric signals measured at the same time by using a limited threshold value. So far, platelets in whole blood analysis,Red blood cell testA common analytical system is used. However, because the measured signals of platelets and red blood cells often cross, for example, the pulse signal of large platelets may be mistaken for red blood cells and counted, and the pulse signal of small red blood cells may enter the platelet channel, resulting in experimental errors. The manufacturers of blood cell analyzers use a variety of advanced technologies to reduceplatelet count We will introduce the interference of
Sweep flow technology: because platelets and red blood cells are counted in the same counting pool, the volume of red blood cells is large, and a large pulse will be formed when passing through the central counting sensing area. If there is backflow, a small pulse will be generated at the same time because the eddy current enters the edge of the sensing area again, so that the electrode may sense a small pulse equivalent to the size of platelets,The number of platelets is falsely increased. The scavenging technology is that while counting red blood cells and platelets, there is a stable liquid flow behind the red blood cell counting hole, so that the red blood cells can be immediately washed away to prevent them from being counted as platelets when they return to the sensing area.
Anti reflux device: in order to prevent the counted red blood cells from returning to the sensing area, a small plate with a hole is installed inside the hole of the red blood cell counting pool. The diameter of the hole on the plate is slightly larger than that of the red blood cell counting hole, just behind the counting hole, outside the sensing area. When counting cells, due to the effect of negative pressure, the cells quickly pass through the sensing area of the small hole and pass through the small hole of the baffle,Even if eddy current is generated outside the baffle, red blood cells will be blocked outside the sensing area, which will not affect the platelet count.
Sheath flow technology: in order to avoid the blood cells flowing from the edge of the hole and the influence of turbulence and eddy current during counting, the sheath flow technology was invented. The specific method is to use a capillary tube to aim at the hole tube, and the cell suspension is ejected from the capillary tube. At the same time, the cell suspension flows with the sheath flowing around the allergic zone, ensuring that the cell suspension forms a single arranged cell flow in the middle,It is surrounded by sheath fluid. The sheath flow technology can be applied to two cell counting principles: one is the electrical impedance principle. The sheath flow counts cells through the sensitive area of the eyelet;The other is the principle of laser counting. The cell fluid flow chamber is long and vertically intersects with the laser. The laser beam will produce light scattering after irradiating each passing cell, and then count the cells according to this principle.
Floating boundary mark: the volume of red blood cells and platelets in normal samples is quite different. Generally, the boundary between red blood cells and platelets is set at 35fl. The large ones are red blood cells, the small ones are platelets, and some others are set at 30fl or 20fl. However, under some pathological conditions, large platelets may exceed the 35fl boundary, resulting in missing platelet count and low results;Conversely, if the red blood cell volume is small (such as iron deficiency anemia,Thalassemia）, some small red blood cells may be mistakenly counted as platelets, which makes the platelet count higher. In order to get more accurate results, the counter uses the computer to find the lowest point of the histogram between 5-35fl, so as to determine the boundary between red blood cells and platelets. This can make the counted values conform to the actual situation. Because the boundary between various cells can move left or right with the actual size of the cells,So it is calledfloating threshold （floating threshold）。
In addition, there are extended count, fitting curve and other techniques to ensure the accuracy of counting results and volume distribution map.
In the early single classification instrument, WBC counting is to dilute the patient's blood sample in a certain proportion after anticoagulation, and then add hemolytic agent (the role is to shrink the cell membrane, and the surrounding cytoplasm slowly diffuses from the cell, but the cell particles are still there), so that the patient's blood sample after such pretreatment becomessuspended particles And make it flow through a micropore made of ruby within a certain time. Different particles can be tested with micropores of different sizes. Generally, the size of the measured micropore of white blood cells is about 100 * 70 microns in length * diameter.Later, on the basis of the single classification instrument, many companies will generate electric pulses of different sizes by using the different sizes of the white blood cells after hemolysis treatment. The corresponding cell parameters can be preliminarily confirmed through the calculation of each channel of the computer in the instrument, and the cells can be divided into lymphocytes (small cell subgroup), neutrophils (monocyte subgroup) and granulocytes (large cell subgroup)Three classification counts. Since the liquid flow focusing resistance method is used to overcome the problems such as micropore plugging and liquid backflow, the constant volume method is used to overcome the error caused by unstable negative pressure, andsampleMultiple procedures such as dilution and addition of hemolytic agent are completed at one time in the machine, which improves the degree of automation. On the circuit, errors caused by multiple particles entering the micropore sensitive zone at the same time are automatically corrected in the channel. After processing by the CPU, the data are read out on the display, printer in the form of data charts, histograms, etc. The instrument software provides a human-computer interface,It can easily complete calibration, quality control, measurement, flushing and other daily operations, and has nearly 20 reported parameters. This kind of instrument has been widely used in small and medium-sized hospitals due to its structure and circuit have been greatly improved compared with single category instruments, and its performance is stable.
Recent improvements in the testing principle of blood cell analyzer are mainly reflected inLeukocyte classificationFor WBC, from single classification to three classification, five classification or even nine classification, the blood cell measurement and analysis method is not limited to a single method, but has developed to use a variety of physical and chemical methods to process white blood cells, use advanced computer technology to distinguish, identify the cell differences between the cells treated by the above methods, and analyze experimental data comprehensively,The combined detection method represents the latest development trend of blood cell analyzer, such as STKS and GEN of Kurt CompanyS uses electrical impedance, laser and electromagnetic wave technology. Bayer's ADVIA series uses the principle of combining chemical reaction and laser technology to determine the five classifications of white blood cells. Abbott's CD-3500 uses electrical impedance and light scattering technology. Sisen Meikang's XE-2100/SE-9500 uses vulcanizationamino acidAnd special hemolytic agents, electrical impedance and radio frequency technology to detect immature cells. The advent of these instruments has greatly provided the accuracy of automatic instruments for leukocyte classification, which has brought the development of instruments to a new stage.
The following is an introduction to the different methods used by major manufacturers to classify white blood cells.
VCS technology is volume measurement, high-energy electromagnetic wave conductivity and laser scattering technology.
V represents volume. Coulter still uses electrical impedance method to count blood cells and measure volume.C represents the conductivity of a beam of electromagnetic wave penetrating the cell, which depends on the size and internal structure of the cell. Usually, we use the corrected conductivity to reflect the internal structure of the cell, such as the size of the nucleus, the ratio of nucleus to cytoplasm, and the size and density of the plasmid in the cell. Therefore, the conductivity can distinguish two groups of cell groups with identical volume.For example, small lymphocytes and basophils with a diameter of 9-12umS represents light scattering, which can be based on the cell surfaceBright lightScattering features classify cells.The monochromatic beam generated by the laser light source directly enters the sensitive area of the counting cell, and each cell is scanned at different angles (10 °~70 °) to determine itsScattered light intensityTo provideCellular structure, light scattering information of morphologyGranulosa cellThe light scattering intensity is stronger than that of fine particle cells, so the light scattering has a good ability to distinguish the configuration and quality of cell particles.
VCS white blood cell classification principle
VCS technology can make white blood cells in the same natural conditions as the body to get the test results.First, add hemolytic agent (only acting on red blood cells) to the sample to dissolve red blood cells, and then add anti hemolytic agent (stabilise) to neutralize the hemolytic agent, so that the surface, cytoplasm, cell size and other characteristics of white blood cells remain the same as those in the body, depending on the cell volume and surface characteristics of different cells,There is little chance that the internal structure, such as the proportion of nucleoplasm and the configuration and quality of particles, is completely consistent. In addition, the instrument is equipped with advanced software, which can be adjusted as the flow cytometer. The threshold can be set, which can better separate the cells in three-dimensional images to achieve more accurate classification, and can prompt immature white blood cells,Heterotypic lymphocyteEtc.In addition, the anti CD4 and anti CD8 monoclonal antibodiespolystyreneThe microspheres are added to the blood, so that the lymphocytes containing the corresponding surface (antigen) markers can combine with the corresponding microspheres to change the VCS properties of the cells. CD4 and CD8 lymphocytes are directly counted on the analyzer, and the ratio is calculated. The instrument produced on this principle is represented by GEN · S cell analyzer.
Such instruments represented by ADVIA120 jointly apply laser scattering andPeroxidase stainingTechnical progressDifferential white blood cell countThe scattered light measured at different angles will be different due to different cell surface structures when counting blood cells with laser scattering technology.This instrument has four measurement channels: hemoglobin measurement channel, red blood cell/platelet measurement channel, basophil measurement channel, peroxidase measurement (leukocyte classification) channel. It uses the difference of five leukocyte peroxidase activities to stain white blood cells and determine theirEnzyme reactionIntensity, white blood cells were analyzed.During the test, each cell produces two signals: histochemical staining results and light scattering results.It uses the X axis to represent the absorbance (histochemical staining enzyme reaction intensity) and the Y axis to represent the light scattering (cell size), which are located together on the cell diagram (see Figure 2). The computer system analyzes and processes the stored data, and calculates the total number and classification of white blood cells in combination with the results of basophilic or lobulated cell channels.
The order of peroxidase activity of five kinds of leukocytes in blood is: eosinophil>neutrophil>monocyte.Lymphocytes and basophils are free of peroxidase. Add the blood to be tested into the isotonic liquid of detergent and formaldehyde for incubation, and then addhydrogen peroxide（HtwoOtwo）And tetrachloro naphthol, the intracellular peroxidase decomposes to produce [O] -, which makes tetrachloro naphthol color and precipitate, and locate at the enzyme reaction site. Due to the different intensity of enzyme reaction, the laser beam irradiates cells at low angle (0 ° - 5 °) and high angle (5 ° - 14 °)The measured scattering intensity is also different. The low angle reflects the cell size: because basophils remain insoluble (large cells) in this hemolytic agent, the scattering intensity is strong;It reflects the number and size of nuclear lobes from a high angle. There are many nuclear lobes and large nuclei cause strong scattering. Finally, it is comprehensively processed and analyzed by the computer to give a more accurate total number of white blood cells and classified count, which also includes large non staining cell groups, namely atypical lymphocytes or peroxidase negative immature cells, so it is called six classifications.The instrument uses laser scattering method to detect red blood cells and platelets, and reagents are required to be added;At the same time, the diluent of red blood cells can be added withFluorescent dyeAfter laser irradiation and excitation, the reticulocytes were counted and classified, and eight reticulocytes parameters were obtained.
Because it uses chemical staining method to analyze the cell type, it uses 11 reagents for testing, and the running cost is high.
Multi angle polarized light scattering (MAPSS) technology adopted by Abbott.
Such instruments, represented by CD-3500 and CD-3000 blood cell analyzers, use multi angle polarized light scattering technology to classify and count white blood cells. The principle is that after the sheath fluid and blood sample are mixed in proper proportion, the internal structure of white blood cells is basically unchanged (only the structure of alkaline granulocyte particles is slightly changed due to its hygroscopic characteristics),The red blood cell membrane in the sheath fluid is complete and equal to the absorbance index of the sheath fluid, so it will not interfere with the detection of white blood cells. Single arrayed cells (concentrated in a small stream of fluid with a diameter of 30um) are irradiated with a polarized laser beam, and the cells are further distinguished. This technology uses the 10 ° narrow angle and polarization plus and minus polarization detection methods rarely used by other instruments,The resolution is improved. The first step is to test the neutral/monocytes, use the scattering data of 0 ° - 90 °, and then measure the diffraction difference of 90 ° D to separate the eosinophils and neutrophils. The basophils, lymphocytes and monocytes produce different scattered light according to their size and complexity of internal structure,It is distinguished by adjustable threshold. It automatically stores the analysis data with a specific program and is processed by computer software. Six scatter plots and two histograms are displayed on the screen.
Sysmex's radio frequency (RF) plus DC impedance white blood cell classification technology
Typical models, such as SysmexSE-9000/SE-9500/XE-2100, have four different detection systems. Samples are treated with special cell staining technology, and then RF and DC technologies are used to classify and count white blood cells. The following four detection systems are used:
Lymphocyte, monocyte, granulocyte (neutrophil, eosinophil, basophil) detection system: the system adopts the combined detection mode of electrical impedance and radio frequency, and uses a mild hemolytic agent, which has little impact on the nuclear and cell types.There are DC and high-frequency transmitters on the inner and outer electrodes. Since DC cannot reach the cytoplasm and nucleoplasm, and RF power penetrates into the cell to measure the size of the nucleus and the number of particles, the number and height of these two different pulse signals comprehensively reflect the number, size (DC), and nuclear and particle density (RF) of cells.Because the size, cytoplasmic content, nuclear morphology and density of lymphocytes, monocytes and granulocytes are quite different, their proportions can be obtained by scanning.
Eosinophil detection system: the system counts by means of electrical impedance. After the blood is divided by a blood divider, part of the blood andEosinophil countThe hemolytic agent is mixed. The specific hemolytic agent makes all cells except eosinophils dissolve or shrink. This liquid containing intact eosinophils is counted by impedance circuit.
Basophil system: The detection principle of this system is the same as that of eosinophils, but its hemolytic agent can only retain basophils in the blood.
Juvenile cell detection system: the system also counts by means of electrical impedance. Its principle is due to thelipidThere are fewer mature cells. After adding sulfurized amino acids to the cell suspension, due to the different lipid occupation, more sulfurized amino acids are bound to the immature cells than to the mature cells, and they are resistant to hemolytic agents, so they can keep the morphology of the immature cells intact and dissolve the mature cells, which can be detected by impedance method.
Reticulocyte count
Reticulocyte count is an important index reflecting the hematopoietic function of bone marrow. Up to now, microscopic visual measurement is still widely used in China. Due to subjective influence, its counting accuracy is poor.In the early 1990s, Japan's SYSMEX Company first launched the R-1000 network red blood cell analyzer, and began to use the analyzer instead of visual measurement. Good results have been achieved in both experimental methods and clinical applications.
Reticulocyte isLate erythroblastThe transitional cells between denucleated and fully mature red blood cells are named after the residual basophils in their cytoplasm, which can be dyed into blue fine particles or nets in vivo.During the development of red blood cells, RNA content has obvious regular changes, that is, it gradually decreases from relatively rich in the original stage to disappear or nearly disappear after the cells are fully maturestayFlow cytometryIn the measurement of RNA, some dyes are generally used to combine with RNA in reticulocyte to emit fluorescence of a specific color, and RNA can accurately represent the percentage of reticulocyte in mature red blood cells (RET%).
Since 1993, blood cell analyzers capable of net red counting have been introduced one after another, making the application of blood cell analyzers enter a new stage.The high-end models of Coulter, Abbott, Bayer, Sysmex and many other manufacturers all have the function of reticulocyte counting and analysis.The detection principle is roughly represented by Coulter Maxam and Technicon H * 3.Coulter Maxam uses two reagents, one is RNA in red blood cells stained with new methylene blue, the other is "transparent" agent, which makes hemoglobin in red blood cells overflow and become "shadow cells" to reduce test interference. The processed blood is detected by the VCS principle on the instrument, and RET #, RET%, mean volume of reticulocyte (MCVr) and reticulocyte maturity index (MI) can be obtained.The experiment proved that the results were highly correlated with the FCM method (r=0.961).Technicon H * 3 test reticulocyte, first add 3ul blood into the standardized dye solution and incubate it for 15 minutes, then convert the instrument to the reticulocyte counting program for detection, and then obtain the experimental parameters of reticulocyte.It includes RET #, RET%, MCVr, RDWr (reticulocyte volume distribution width), CHr (reticulocyte hemoglobin volume distribution width), HDWr (reticulocyte distribution width) and reticulocyte classification. According to the fluorescence intensity, reticulocyte can be divided into low (LFR), medium (MFR) and high (HFR) parts.Juvenile reticulum shows the strongest fluorescence, whereas mature red blood cells show little or no fluorescence.
To sum up, due to the rapid development of comprehensive high-tech in recent years, the latest electronic, optical, chemical and computer technologies are constantly used in the blood cell analyzer, so as to continuously meet the requirements of clinical work for blood cell analysis. All manufacturers are developing towards high speed, multi parameter, multi-functional synthesis and more flexible and convenient operation,Recently, various manufacturers have launched a fully automatic pipeline of blood analyzer, which automatically completes a series of steps such as routine blood analysis, reticulocyte analysis, blood slice preparation (selection, smearing, numbering, dyeing, drying) through the instrument. Blood is first detected by the blood cell analyzer, and whether to count reticulocytes is determined according to the situation of red blood cells,Change the angle and speed of the smearer according to HCT to ensure qualified blood smears. According to the changes of experimental data and histograms, the computer selects whether further microscopic examination is required, especially the application of the automatic sample adding system and the vacuum blood collection tube, which may not only avoid the random error of the experiment, but also speed up the processing of samples,Moreover, it has avoided the blood line infection caused by some experimental links, played a key role in the labor protection of staff, and made many operations more standardized, becoming the trend of instrument use and development.[2]
Classification determination
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Five classification of blood cells and its application progress.
Hematology analyzer is one of the most widely used instruments in hospital clinical laboratory, which is used to analyze the number and heterogeneity of blood cells in a certain volume.Since the 1990s, with the application of electronic technology, flow cytometry, laser technology, electronic computer technology, new fluorescent chemicals and other high-tech technologies in blood cell analyzers, the detection principle of blood cell analyzers has been constantly improved, the measurement parameters have been continuously increased, and the detection level has been constantly improved, especially in the five classification technology of white blood cells,It has developed to use multiple technologies (such as radio frequency, cytochemistry staining, flow cytometry, fluorescence staining, etc.) to jointly detect a white blood cell at the same time. Then, it uses advanced computer technology to distinguish and distinguish the cell differences between the cells treated by the above methods. By synthesizing the experimental data, it can obtain more accurate results of white blood cell classification.It provides an important laboratory basis for the diagnosis and treatment of clinical diseases.in recent years.Hematology analyzer that can count white blood cells in five categories has been widely used.In this paper, the common techniques and the latest application progress in the five classification determination of blood cells are reviewed.
The principle of blood cell five classification technology
1. Flow cytometry
Flow cytometry (FCM) is a comprehensive application of optics, mechanics, fluid mechanicselectronic computer, cell biology, molecular immunology and other disciplines and technologies to make the measured solution flow through the measurement area, and detect the physical and chemical characteristics of each cell one by one, so as to carry out rapid quantitative measurement and analysis of high-speed flowing cells or subcells.
First, the cells to be tested are pressed into the flow chamber after being treated or dyed. At the same time, the buffer solution without cells is ejected from the sheath tube under high pressure. The population direction of the sheath tube is at a certain angle with the flow of the sample to be tested, so that the sheath can be wrapped around the sample and flow at a high speed, forming a round flow beam. The cells to be tested are arranged in a single line under wrapping,It passes through the detection area in turn and generates scattered light and excited fluorescence under the irradiation of laser beam.These two light source signals reflect the size of cell volume and internal information respectivelythroughPhotomultiplier tubeAfter receiving, it can be converted into electrical signals, and then converted into digital signals that can be recognized by the computer through analog to digital converters. After computer processing, the analysis results can be displayed on the screen.
In order to ensure that cells pass through the detection area one by one in a single arrangement, sheath flow technologyFlow cytometryIt is widely used in.according tolaminar flowIn theory, the velocity and pressure of the two liquids are different.Under certain conditions, the sample solutionsheath They can be kept separate from each other and coaxial in the flow.At the same time, sheath liquid flow can accelerate the flow of particles in the sample solution and force their flow path to remain on the axis of the liquid flow, so that cells can pass through the detection area one by one in a single array, which is the so-called liquid flow focusing principle
2. Impedance method
according tocoulter principle Dilute the bad conductor blood into isotonic electrolyte in a certain proportion, add a constant current source on both sides of the hole electrode, and make the diluted blood cells pass through the hole under the effect of negative pressure.When a cell passes through the cross section, it will generate a corresponding pulse due to the increase of resistance. The amplitude of the pulse is proportional to the volume of the cell, and the frequency of the pulse is proportional to the number of cells.This is the famous Kurt principle or the variable resistance pulse principle.Kurt principle can be used to effectively distinguish lymph and monocytes.
According to the light scattering theory, when the laser irradiates every cell flowing through the flow chamber, due to the physical characteristics of the cell, part of the light is scattered from the cell through different angles.Wherein, small forward angleScattered lightThe light intensity can reflect the cell volume;The light intensity of large angle scattered light can reflect the nucleus, plasmaComplexityAnd cell granules;The light intensity of the side scattered light can reflect the cell membranenuclear membraneChanges in cytoplasm.Therefore, cells can be classified according to the light scattering characteristics of cells.The monochromatic beam generated by the laser light source directly enters the sensitive area of the counting cell, scans and analyzes each cell at different angles (10 °~70 °), and measures its scattered light intensity, so as to provide light scattering information of cell structure and morphology.Because the scattering intensity of coarse-grained cells is stronger than that of fine-grained cells, light scattering has a good ability to distinguish the configuration and quality of cell particles.
Generation process
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Hemopoiesis
In the process of life, blood cells are constantly metabolized.Every day, some of the old blood cells are destroyed, while some of the new blood cells enter the blood circulation.useIsotope labelingAccording to the measurement, the average life of red blood cells is about 120 days, while the life of granular white blood cells and platelets is shorter, and the life span generally does not exceed 10 days.The survival period of lymphocytes varies from several hours to several years.The formation and destruction of blood cells keep a dynamic balance.Therefore, the number of blood cells in normal human blood remains relatively stable
Red blood cell lineThe process of development is fromProerythrocytesStarted.The proerythrocytes are large and round,ChromatinIt is fine grained, with 1-3 nucleoli, and the cytoplasm is strongly alkaline.When proerythrocytes develop into erythroblasts, the nuclear chromatin becomes thicker and hemoglobin begins to be synthesized in the cytoplasm.The erythroblast develops intoErythroblast。The cell body of the erythroblast is small, the nuclear chromatin is thick, and the hemoglobin in the cytoplasm gradually increases.Mesoblasts proliferate and differentiate again, and develop into smaller cell bodiesNuclear pyknosisLate erythroblasts whose cytoplasm is full of hemoglobin.The late erythroblasts have no ability to divide. After the nuclei are removed, they become reticulocytes, which then develop into mature erythrocytes and are released into the blood circulation.[1]
Medullary Hematopoiesis
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Hematopoietic pluripotency of blood cells derived from bone marrowstem cells(Multipotential stem cell)。In addition to the ability to proliferate, stem cells can migrate out of bone marrow hematopoietic tissue under certain conditions, and form with blood flow to extramedullary tissueHematopoietic cellsSummary, calledColony forming unit。Each summary is composed of many differentiated cells of the same type, which are derived from the division and differentiation of a stem cell.Although stem cells have the ability to replicate and differentiate themselves into various blood cells, in general, they are not in the state of proliferation, but in the resting G0 phase.
Primitive stem cells can differentiate into two branches: one is colony forming unit cells (CFU-C), also known as bone marrow stem cells, which are pluripotent stem cells of red blood cells, neutrophils, eosinophils and platelets.Colony forming unit cells are mainly derived from bone marrow. Before they develop into red blood cells, granulocytes and megakaryocytes, they must pass through theTargeted stem cellsPhase.The other branch is lymphoid stem cells, also known as lymphoid stem cellsHigher animalimmune systemIts differentiation and development are closely related to the stimulation of antigen.Lymph stem cells are also pluripotent stem cells, which can differentiate into two different directional stem cells, one isthymusDerived T lymphocytes or T cells, one is bone marrow dependentB lymphocytesB cells, or B cells, are transformed into prolymphoblastic cells and protoplasmic cells through the stimulation of corresponding antigens, and then gradually mature, called lymphocytes and plasma cells, respectively.
In a word, blood cells are hematopoietic pluripotent stem cells derived from bone marrow. First, pluripotent stem cells differentiate into colony forming unit cells (bone marrow stem cells) and lymphoid stem cells, and then bone marrow stem cells differentiate into directional stem cells of various lines. After primitive and immature stages, development and proliferation finally mature into red blood cells, granulocytes, monocytes and platelets.Lymphoid stem cells, on the other hand, undergo two stages of primordial and infantile development, proliferation and maturation;Under the stimulation of antigen, the protolymphoid cells and protoplasmic cells were transformed respectively, and proliferated and matured into immunocompetent lymphocytes and plasma cells.
The proliferation of blood cells is carried out in the way of division, but only immature cells have the ability to divide. Once the development reaches a certain stage, the proliferation will stop.
division
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First, mitosis (indirect division)
During cell division, special mitoses appear, so it is called mitosis.Mitosis is the main form of blood cell proliferation.There are no mitotic cells in the circulating blood of normal people.The number of mitotic cells in hematopoietic tissue reflects the degree and state of their proliferation.The process of division can be divided into four stages, mainly manifested in nuclear changes.
(1) Prophase (also known as monofilament stage): when the cell starts to divide, the cell body becomes spherical, the nucleus expands, the nuclear chromatin gathers into a single columnar chromosome, and the nuclear membrane and nucleosome disappear, like a silk ball.The cytoplasm became pale, the organelles and inclusions were temporarily hidden, and the centrosome was displayed.
(2) The middle stage (also known as the single star stage): the centrosome begins to split, and gradually moves to the two poles. There are filaments connected between them, which are shaped as spindles, called spindles.The nuclear chromosomes are arranged like stars or chrysanthemums, and are located in the middle plane of the spindleEquatorial plateOn.
(3) Later stage (also known as double star stage): each chromosome divides into two evenly, and the filament shrinks, so that the chromosomes after division follow the centrosome to the two ends of the cell, and are arranged into two stars respectively.The cytoplasm began to shrink.
(4) End stage (also known as filamentary stage): the chromosomes tending to both ends of the cell begin to gather into filamentary globules, and then disperse into chromatin, forming small nuclei with two new nuclei. At this time, the cytoplasm can form a dumbbell shape, and finally the cytoplasm separates, and the cell divides into two.
The expression form of this division process is relatively simple. Generally, the nucleosome of the cell starts to separate first, then the surface of the cell nucleus shrinks, and then gradually deepens and decomposes into two, followed by the separation of the cytoplasm, thus directly forming two daughter cells.
Hemopoietic organ
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Blood cells are generated in hematopoietic organsembryoThe main hematopoietic organs are not the same at different stages of development after birth.
Hematopoietic organs in embryonic stage
(1)mesoblastic hematopoiesis It occurs in 1-2 months of the embryo.The yolk sac is the first place where hematopoiesis occurs.VitellineMesodermInterstitial cellyeshemopoietic systemThe primordium of the yolk sacBlood island, blood island peripheralcell differentiationIt develops into primitive blood cells, which further differentiate into primary primitive red blood cells with hemoglobin in the cytoplasm, that is, embryonic blood cells.
(2) Hematopoietic phase of liver: it occurs in 2-5 months of embryo.The yolk sac atrophied and degenerated, and its hematopoietic function was replaced by the liver.It can not only differentiate into primary primary red blood cells, but also differentiate into secondary primary red blood cells, which gradually develop into red blood cells and enter the blood through the sinuses.At this time, the liver's hematopoietic activity is very active.The spleen also participates in hematopoiesis around the third month of the fetus, mainly producing red blood cells, granulocytes, lymphocytes and monocytes.By the fifth month, the spleen's hematopoietic function gradually declined, and only produced lymphocytes and monocytes, while this hematopoietic activity lasted for life.
(3) Bone marrow hematopoiesis stage: this stage starts from the 4th month of the embryo.The fetus begins to develop bone marrow hematopoietic tissue, which initially only produces granulocytes, followed by red blood cells and megakaryocytes.At the same time of bone marrow hematopoiesis, thymus andlymph glandHematopoietic activity also began.The thymus generates lymphocytes and maintains this function after birth;Lymph nodes mainly produce lymphocytes and plasma cells, and also participate in the production of red blood cells in the early stage.
The above three stages are intertwined with each other, which is actually difficult to completely separate.
Hematopoietic organs after birth
(1) Bone marrow: bone marrow is the only hematopoietic organ that generates red blood cells, granulocytes and megakaryocytes after birth, as well as lymphocytes and monocytes.From newborn to 4-year-old children, the whole body bone marrow has active hematopoietic function.At the age of 5-7, it begins to appear between the hematopoietic cells of tubular bonefat cells。The range of red marrow in tubular bone gradually decreases with age,adipose tissueGradually, the bone marrow turns yellow, which is called yellow bone marrow.Although there is no hemopoiesis in the yellow marrow, there is still potential hemopoietic function.About 18-20 years old, the red pulp is only limited to the skull, sternum, spine, ilium and other flat bones, as well as the proximal end of the humerus and femur.Red pulp accounts for about half of the total bone marrow.Hematopoietic activity of red pulp will last for life, but its activity may slightly decrease with age.
The bone marrow is a spongy, gelatinous or fatty tissue that is sealed in the hard bone marrow cavity.It is divided into red pulp (hematopoietic cells) and yellow pulp (fat cells). The weight of normal adult bone marrow is 1600-3700g, about 3.4% - 5.9% of the body weight, of which the weight of red pulp is about 1000g.
Bone marrow has complex and richVascular system。The nutrient arteries in human bone marrow supply the capillaries in the whole marrow cavity.All arteries of the bone marrow are accompanied by nerve bundles. The nerve fibers originate from the spinal nerves and enter the marrow cavity with the arteries from the nutrient holes. They are distributed in the marrow cavity in parallel with the nutrient arteries and terminate in the smooth muscle fibers of the artery wall.The bone marrow is filled with blood sinusesParenchymal cellHematopoietic cells, bone marrow hematopoiesisPluripotent stem cellDifferentiation and hematopoiesis of erythroid, granuloid and megakaryoid lineagesMicroenvironmentofHematopoietic microenvironmentIt may be composed of blood vessels, macrophages, nerves and matrix.In terms of its function, the hematopoietic microenvironment should include all factors that affect the hematopoietic function, of which the vascular factor is very important, because all kinds of hematopoietic substances and their stimulators must enter the bone marrow through the blood vessels in order to hematopoiesis.There is a barrier between the hematopoietic site and the blood circulation, namely the bone marrow blood barrier, which has the function of controlling blood cells to enter and exit the bone marrow.
(2) Thymus gland: thymus gland undergoes certain changes from birth to old age.After puberty, hematopoietic activity gradually disappears and is replaced by adipose tissue.
Thymus not onlyEmbryonic stageIt is one of the important hemopoietic organs of, and still has active hemopoietic function after birth, especially in the two years after birth, the gland tissue grows rapidly, and the hemopoietic activity is also very vigorous.Thymic integumentconnective tissueDivided into many incomplete lobules.The surrounding part of the lobule is called cortex, and the central part is called medulla.The cortex is full of dense lymphocytes. The shallowest layer is more primitive lymphocytes, the middle layer is medium sized lymphocytes, and the deep layer is small lymphocytes. From the shallow layer to the deep layer, stem cells proliferate and differentiate intoThymus dependent lymphocyte(T cells).Although the adult thymus is atrophic, T cells are already aroundlymphoid tissueSettle down in China and be able to breed by yourself.In addition to delivering T lymphocytes to the surrounding lymphoid tissues, the thymus is alsoepitheliumThe sex network secretes thymosin, and the stem cellsThymic hormoneIt was induced to differentiate into immunocompetent T lymphocytes.
(3) Spleen: The spleen is the largest in the human bodyLymphoid organIts essence is divided into two parts: red pulp and white pulp.The white pulp includes the lymphatic sheath around the central artery and spleen nodules.Around the central artery is splenicThymus dependent regionT lymphocytes are mainly present in the region.The splenic nodules areLymph nodeIn the summary, there are germinal centers, mainly B lymphocytes.In addition to producing lymphocytes and monocytes, the spleen also has the function of storing blood and destroying aging red blood cells.
(4) The lymph nodes of appendix and ileum, where the stem cells of bone marrow gather, can induce the proliferation of stem cells to differentiate into bone marrow dependent lymphocytes (B cells) and spread in the surrounding lymphoid organs.
(5) Lymph node: It is divided into the surrounding cortex and the central medulla.Superficial cortexLymphoid folliclesThe center of B cell proliferation is called germinal center orReaction center；The deep cortex is mainly composed of T cells from the thymus, called thymus dependent area;Under the stimulation of antigen, T lymphocytes can proliferate and produce a large number of sensitized small lymphocytes, which directly act on antigen through blood flow.The medulla is mainly composed ofMedullary cord(Lymphatic cord) and lymphatic sinus.The main components of medullary cord are B lymphocytes, plasma cells and macrophages.
The above (2), (3), (4) and (5) parts belong to lymphopoiesis.Lymphatic organs are divided into central lymphoid organs and peripheral lymphoid organs.The lymphoid tissue in the thymus and bone marrow belongs to the central lymphoid organ, which is the place where lymphatic directional stem cells focus;Lymph nodes, spleen and other lymphoid tissues are peripheral lymphoid organs, where differentiated T cells and B cells are located.
(6)Reticuloendothelial system(RES): including spleen and lymph nodesReticular cell, covering liver, bone marrowadrenal cortex, anterior pituitarySinusoid spaceOnendothelial cellsAnd free tissue cells in other organs.Its main cellular component is reticular cells, which can differentiate into phagocytic reticular cells.The monocytes in the blood enter the reticular tissue after myelogenesisHistiocyte；Under certain conditions, it can be transformed into free phagocytes with phagocytic function, forming the so-called monocyteMacrophage system。
Under normal circumstances, infants born 2 months later will never have extramedullary hematopoiesis.Under pathological conditions, hematopoiesis can occur in tissues other than bone marrow, such as spleen, liver, lymph nodes, etc. This is called extramedullary hematopoiesis. This is because these parts retain mesenchymal cells with hematopoiesis ability to restore their embryonic hematopoiesis function.
The average life span of red blood cells is about 120 days.Although senescent red blood cells have no morphological specificity, their functional activities and physical and chemical properties have changed, such as decreased enzyme activity, hemoglobin denaturation, increased membrane fragility, and changes in surface charges. As a result, the ability of cells to combine with oxygen is reduced and easily broken.Senile red blood cells are mostly engulfed by macrophages in the spleen, bone marrow and liver. At the same time, the same amount of red blood cells are generated and released from the red bone marrow into the peripheral blood to maintain a relatively constant number of red blood cells.
Erythrocytes have electrorheological properties, and the nature and quantity of their surface charges are closely related to the hemorheological properties, the interaction between cells, and the lifespan of red blood cells.Used by Piper in 1959NeuraminidaseTreatment of human red blood cells resulted in a significant decrease in the electrophoresis rate of red blood cells. Further research confirmed that this was related to the glycoprotein or sialic acid or N-acetyl neuroamino acid on the surface of red blood cells. The carboxyl group generated by ionization in plasma was the main charged group that determined the negative charge on the surface of red blood cells.The content of sialic acid released by human or mammalian red blood cells after neuraminidase treatment was positively correlated with the decrease of erythrocyte electrophoresis rate.In addition, it was found that part of the charge carried by red blood cells was also related to amino groups and phosphate groups through the combination degree of charged groups and cations and the corresponding changes in spectroscopy. When the latter group decreased, the electrophoresis rate of red blood cells could be reduced to a certain extent.
