Hepatocyte

Animal organ cell

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The liver is composed of hepatocytes, which are too small to be seen with the naked eye and can only be seen through a microscope. There are about 2.5 billion hepatocytes in human liver, and 5000 hepatocytes form a hepatic lobule Hepatic lobule The total number is about 500000. Hepatocytes are polygonal, with a diameter of about 20-30/μ m, 6-8 sides, and different Physiological conditions There are differences in the size of the lower part, such as the volume of hepatocytes becomes larger when hungry. Each hepatocyte surface can be divided into Sinusoid space Face, hepatocyte face and Bile canaliculus There are three kinds of faces. There are many complicated fine structures in the liver cells, such as nucleus 、 cytoplasm 、 mitochondrion 、 Endoplasmic reticulum 、 lysosome 、 Golgi apparatus , and drink vacuole Etc.

Chinese name: Hepatocyte
Foreign name: hepatocyte,hepatic cells,liver cells
Shape: Polygon

Diameter: 20-30/Plus (micron)
Composition: DNA and histones
Applied discipline: Zoology - Animal Histology

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brief introduction

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HE staining of human hepatocyte slice LM10 * 40 times

Hepatocyte hepatocyte ,hepatic cells,liver cellsL

M (light lens): polyhedron; The core is large and round, centered, Euchromatin Rich, some have dual cores or polyploid Nuclear; Cytoplasm Acidophilic , with dispersion distribution Basophil Lumps.

EM (Electron microscope): (1) There are three functional surfaces → Blood sinus Face → Bile canaliculus Face → Cell junction Face: Yes Tight connection 、 Desmosome 、 gap junction ； (2) Organelles. to develop Rough endoplasmic reticulum : Synthesis albumin 、 Fibrinogen 、 prothrombin 、 Lipoprotein and complement etc. Plasma protein ； Smooth endoplasmic reticulum : Participation Biotransformation And metabolism, such as bile Synthesis Lipid metabolism 、 Carbohydrate metabolism 、 Hormone metabolism And transformation of organic foreign matter; Golgi Complex: involved in protein processing and bile excretion mitochondrion 、 lysosome and Peroxisomes Richness; (3) With Glycogen 、 Fat drop , pigment, etc.

Hepatocyte nucleus

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The nucleus of liver is mainly composed of Deoxyribonucleic acid (DNA) and Histone Etc. DNA is the material basis of heredity, and it has replication genetic information Function of. suffer from hepatitis When, hepatitis virus The virus gene may combine (integrate) with deoxyribonucleic acid (DNA) in the nucleus of liver when invading into the nucleus of liver. Once consolidated, HBsAg That is, it is difficult to remove HBsAg, which results in long-term carrying. In addition, DNA may act on its own Template synthesis Messenger ribonucleic acid (mRNA) to control the synthesis of various corresponding proteins in the cytoplasm. If the hepatocyte nucleus is obviously damaged, it means that the whole hepatocyte is disintegrated and destroyed.

mitochondrion

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Hepatocyte mitochondrion There are many, about 1000 in each cell, all over the cytoplasm. The size and shape of mitochondria in hepatocytes of different parts of the hepatic lobule are not completely consistent Physiological conditions Lower, mostly round and oval, with a diameter of 0.4-0.8 μ m。 Common fundamentals of mitochondria morphological structure It is characterized by external double-layer boundary membrane-- External membrane and Internal limiting membrane The inner limiting membrane extends and turns to the interior of mitochondria, forming many ridges. The inner limiting membrane divides mitochondria into inner and outer chambers. The outer chamber is between the inner and outer membranes, and the inner chamber is surrounded by the inner limiting membrane, which is full of matrix.

stay mitochondrion The surface of the ridge and the matrix surface of the internal limiting membrane are attached with Dense arrangement A matchhead like subunit of Grana 。 The particle is composed of a spherical head of about 10nm and a short handle of about 3.5nm in width and about 5nm in length. The head extends into the matrix, equivalent to ATP synthase Location, is Oxidative phosphorylation Final synthesis ATP A part of an enzyme. One end of the stalk is connected with the boundary membrane of the ridge and is a connexin, lipid and amino acid It is oxidized into water and carbon dioxide , the released energy passes through this Connexin Transfer to ADP to generate ATP. The subunits of mitochondria are only available in specially treated specimens, such as Cell homogenate And use the hypotonic method to destroy its boundary membrane, expose its ridge, and then Phosphotungstic acid Negative staining , can be seen. But ordinary Ultrathin section This subunit is not found because Osmic acid When fixed, the spherical head is depolymerized. Mitochondrial inner and outer boundary membrane permeability And chemical composition are different from each other. For most low molecular solutes with molecular weight less than 10000, the external membrane can pass through freely, while the internal boundary membrane only allows no charge Relative molecular weight Less than 150 Small molecule Such as water O2 、CO2、 urea and glycerol After passing, glucose, K+, Na+, Cl -, etc. cannot pass through the intima. mitochondrion There are some small electron dense particles in the matrix, which are called mitochondria inner particles or Matrix particle 。 Matrix particles contain Ca2+, Mg2+ plasma 。 Mitochondrial matrix It contains protein (including various enzymes lipid Composition DNA 、 RNA And ribosomes), in addition, there are various Mononucleotide and coenzyme 。 because mitochondrial membrane And matrix contain a lot of enzymes, such as oxidation Of respiratory chain Of Enzyme system ， Oxidative phosphorylation Enzyme system Tricarboxylic acid cycle and Fatty acid oxidation Various metabolic substances are oxidized in mitochondria, and the released energy conversion Into ATP. Therefore, mitochondrion Like an energy center, an electric power generating station, it can continuously provide cells with Life activities The energy required to ensure and promote cells to carry out various complex physiological function 。

Because mitochondria also contain their own genetic material—— Deoxyribonucleic acid It is called mitochondrial deoxyribonucleic acid (mt DNA) or extracellular deoxyribonucleic acid, and its content accounts for about 2% of the total DNA of a cell. In addition, mitochondria also contain DNA Polymerase ， RNA polymerase , amino acid activating enzyme, ribosome, tRNA And mRNA. So it can Self replication and Synthetic protein , self splitting, reproduction and proliferation. Mitochondria are the most sensitive Organelle one of. Under many pathological conditions, mitochondria often undergo various morphological changes first, the most common being mitochondrial swelling, mitochondrial proliferation, hypertrophy, and Inclusions Generation of. [1]

Endoplasmic reticulum

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The endoplasmic reticulum of hepatocytes is abundant and widely distributed. It is related to Golgi The complex and nuclear membrane together form a continuous intracellular network Membrane system 。 Press Capsule Whether the surface is attached Riboribosome , endoplasmic reticulum is divided into two categories: Rough endoplasmic reticulum and Smooth endoplasmic reticulum 。

Rough endoplasmic reticulum

The rough endoplasmic reticulum (RER) forming pool (cistem) has ribose attached to its membrane Ribosome According to the measurement, the total area of endoplasmic reticulum contained in 1mg liver tissue is about 11m2, of which about 2/3 is RER. The distribution is different in different zones of hepatic lobule. RER is particularly abundant in hepatocytes in the peripheral zone of hepatic lobule. On the contrary, the smooth endoplasmic reticulum is located in the central zone of the lobule and Median There are more in hepatocytes than in hepatocytes around lobules. The difference in the distribution of this number is similar to that of hepatocytes in different regions of the lobule Functional characteristics of In a cell, the main function of RER is to generate Output protein (or called Secretory protein ）, such as Plasma albumin 、 α、β Globulin 、 Fibrinogen 、 prothrombin And so on, all synthesized on RER. Neosynthetic protein Through the endoplasmic reticulum into the lumen, via Transport vesicle Ship to Golgi Complex, where processing, concentration Premenstrual Secretory vesicle from cell surface It is released into the hepatic sinusoid. The development of RER reflects the functional state of hepatocytes. Caused by various damage factors Hepatocyte injury Can also be reflected in RER, the most common change is on the RER membrane Polyribosome Disaggregation and threshing（ degranulation ）。 The depolymerization refers to that the polyribosomes are dispersed into monomers, free and dispersed in the cytoplasm, or attached to the rough endoplasmic reticulum membrane. Threshing refers to the shedding of ribosomes attached to the RER membrane, which are scattered in the cytoplasm in the form of monomers. For example, when liver cells are damaged due to carbon tetrachloride poisoning, the depolymerization and degranulation of polyribosomes on the RER membrane can be seen. At this time, protein synthesis They also gather and descend. In case of liver cancer, the number of RERs and tumor cell Of growth rate And malignancy Correlation In the highly differentiated and slow growing cancer cell In, RER is relatively developed. On the contrary, in poorly differentiated and rapidly growing liver cancer cells, RER is often rare, while free polyribosomes are very abundant to meet the needs of rapid growth of cancer cells.

Smooth endoplasmic reticulum

No nuclei attached to the smooth endoplasmic reticulum (SER) membrane Proteosome , which is composed of branched tubules and connected with the RER, and can also be formed by the RER. SER has many functions in liver cells, such as participating in glycogen metabolism Bile secretion , lipid metabolism Steroid hormone Metabolism and detoxification. SER is usually located in Cytoplasm One side is accompanied by glycogen particles. If glycogen is very rich, SER can often be covered to make it indistinguishable. During starvation, glycogen decreased and SER in hepatocytes was more obvious. Since SER contains glucose -6 phosphatase , plus glycogen Structural space Therefore, it is more conducive to glycogen metabolism. SER and bile Secretion related, non Associativity bilirubin After entering hepatocytes from blood Glucuronic acid Transferases Function, become Water solubility Conjugated bilirubin It is good for excretion, Bile salt It is also synthesized on SER. In addition, SER is also involved in fat metabolism. In blood free fatty acids After entering hepatocytes, acylation on SER glycerol Triester, formed by combining with the protein synthesized by RER Very low density lipoprotein Into the sinuses. Detoxification function of liver Also in SER. As SER contains mixed functional oxidase system, the final oxidase is cytochrome P-450 Hazardous substances Such as body Metabolites , drugs Carcinogen , pesticides, etc. can be metabolized so that they can either be detoxified or transformed into substances easy to excrete. It is easy to understand that in the process of chronic drug poisoning (such as sleeping pill 、 Barbiturates poisoning ）The proliferation of SER membrane can be seen. The proliferation of SER membrane is also seen in long-term anti Histamine Drugs, Oral Anti diabetes Drugs and acyeterion When. The proliferation of SER membrane is generally a kind of cell Adaptive response , is the expression of increased function (that is, the induction of enzymes). However, not all SER hyperplasia is accompanied by an increase in function, and sometimes it often presents as an ineffective hyperplasia. stay Cholestasis SER in hepatocyte hyperplasia was in a low activity state. surface antigen Positive hepatitis B In patients, smooth endoplasmic reticulum hyperplasia also occurs in hepatocytes, forming in its tubules Hepatitis B surface antigen 。 At this time, the hepatocytes contain proliferative smooth endoplasmic reticulum, which is indistinct on the tissue section Ground glass Therefore, it is called ground glass cell. Under electron microscope, visible light Hepatitis B surface antigen in the center of the tubule of the facial endoplasmic reticulum. This is important in diagnosis.

Ribosome

Ribosome Riboribosome or ribosome , because it was first found by Palade under electron microscope, it is also called palade body. The ribosomes can be free in the cytoplasm matrix, called free ribosomes, and can also be attached to the endoplasmic reticulum membrane Rough endoplasmic reticulum 。 Hepatocytes are rich in free ribosomes, which are composed of 60s and 40s (S=Svedberg, Settlement coefficient ) Subunit Composition Granular 。 Large subunit diameter is about 23 μ m , slightly conical, containing a central tube, the base It is flat and has a narrow groove. The small subunit is slightly arc-shaped (23nm × 12nm), with one side Exoconvex , concave on one side; stay Magnesium ion Large and small subunits combine when present order form At this time, the concave surface of the small subunit is close to the flat bottom surface of the large subunit, and the middle of the small subunit Dividing line It is fitting with the trench at the bottom of the large subunit to form a tunnel. The main component of ribosome is ribosome Ribonucleic acid （ rRNA ）, they bind to proteins to Nucleoprotein (RNP). The ribosomes can exist alone, that is, they can also be mRNA The filaments connect them together to form a polyribosome. Polyribosome yes Synthetic protein The functional group of, mRNA traverses the tunnel between large and small subunits, newly synthesized Peptide chain It is released from the central tube. When a specific main chain is formed, the ribosome leaves the mRNA and decomposes Chengya Company. When it is necessary to synthesize protein, subunits combine again and further form polyribosomes. Therefore, in the cytoplasm, the monomer and POLYMER It is always in the dynamic change of continuous combination and decomposition with the functional state of cells. The protein synthesized by free ribosomes is mainly used for the growth, division and renewal of hepatocytes.

lysosome

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DeDuve first entered the Rat It was found in the components of hepatocyte homogenate after ultracentrifugation lysosome It was confirmed by electron microscope. Lysosomes are particles surrounded by monolayer boundary membrane, and their size, shape and internal structure are extremely inconsistent. Since all lysosomes contain acid hydrolase Therefore, this enzyme is used as the lysosomal Marker enzyme 。 Lysosomes digest and decompose various endogenous or Exogenous Substance, therefore, can be regarded as intracellular Digestive organ 。 The lysosomes contained in hepatocytes are relatively abundant, which can be divided into two types according to whether they contain substrates: Primary lysosome （primarylysosome）, Secondary lysosome (secondarylysome) and Residuum (residual body)。

Primary lysosome

This class lysosome Only contains hydrolase But there is no substrate, which is wrapped by a single layer of boundary film, and contains electron dense homogeneous material, which is often located near Golgi Complex. primary Lysosomal enzyme stay Rough endoplasmic reticulum It is synthesized and transported to Golgi via vesicles Vesicle It is processed and concentrated, and then expanded and separated from the end of the secretory surface of Golgi flat capsule to form the primary lysosome. The hydrolase contained in lysosome can digest all kinds of Macromolecular compound 。 Under normal physiological conditions, this enzyme is inactive, and Internal surface There is also a layer of charged glycoprotein The protective film is not affected by hydrolase. Moreover, lysosomal membrane also has unique filtration properties, allowing only substances with small molecular weight to pass through. That's a guarantee macromolecule The hydrolytic enzyme of can not escape out of the membrane freely, thus protecting cells from Self digestion 。

Secondary lysosome

This class lysosome In addition to hydrolase, it also contains corresponding substrates and the resulting digestive products. The diversity of secondary lysosome morphology is formed due to the difference of substrate and digestion degree. The secondary lysosomes can be divided into autogenerative , heterogenesis and facultative. Undigested substances remain in lysosomes to form Residuum , also known as post lysosome.

Golgi complex

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Under electron microscope, Golgi The Golgi complex is composed of three basic components, namely, flat Vesicle , vesicles and bullae, mostly located in the area between the nucleus and the bile capillaries.

Flat vesicle

Flat vesicle（ saccule ）It is composed of a group of flat vesicles that are curved in the shape of horseshoe and originate from the outer layer of nuclear membrane. Curved vesicles have two sides (convex and four sides), the convex side is also called forming face, or immature face, close to the nucleus; Concave is the secreting face, or mature face, facing cell membrane 。 The membrane of the formation surface is thin, similar to the cell membrane. Therefore, Golgi vesicles can be regarded as the intermediate differentiation stage between endoplasmic reticulum membrane and cell membrane.

Vesicle

Vesicle（ vesicle ）A large number of vesicles, similar to common pinocytosis vesicles, are often scattered on the formation surface of flat vesicles Golgi The rough endoplasmic reticulum near the complex sprouts and contains protein components synthesized by the rough endoplasmic reticulum, which is transported to Golgi complex The vesicle formation surface of the Membrane fusion The protein enters the vesicle cavity.

Bulla

Bulla（ vacuole ）It is locally expanded from the end of the flat vesicle, also called Secretory vesicle Or concentrated vesicles with secretory substances (such as Lipoprotein 、 bile Components) Break off the flat vesicles and transport them to the sinus cavity or discharge them to capillaries bile duct 。 Perimembrane of secretory facial cells Microfilament 、 microtubule The existence of the system is the necessary prerequisite and guarantee for the realization of this function. The incorporation of vesicles and the disconnection of bullae keep Golgi capsule in the dynamic changes of metabolism. The common pathological changes of Golgi complex are hypertrophy or atrophy. Hypertrophy of Golgi complex is mostly seen in secretory dysfunction with secretion in Golgi bullae retention and Cholestasis Etc. Bile components remain in the secretory vesicles; In nutritional or toxic hepatic steatosis, lipoproteins are retained in Secretory sac In the bubble. The atrophy of Golgi complex is common in the decline of the synthesis function of nucleosomes, such as the reduction of protein synthesis of hepatocytes caused by various toxic factors, that is, the rough endoplasmic reticulum Degranulation And fracture. With Golgi Atrophy or disappearance of complex.

Microbody

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Microbody It is the smallest organelle in the liver cell, which is a round or oval body surrounded by a single-layer boundary membrane. In hepatocytes, microsomes and mitochondrion The proportion of is almost 1:4. Microbody matrix contains catalase And multiple oxidase , such as D- Amino acid oxidase 、 L-amino acid oxidase And L-2- Hydroxy acid Oxidase, etc., so microsomes are also called peroxides（ peroxisome ）。

Peroxides from Rough endoplasmic reticulum , rapid formation, from rough surface Endoplasmic reticulum It only takes about one hour to transport out, and it can exist in cells for 5 days, and disintegrate through autophagy or autolysis process within 4 minutes. It can also be produced by splitting from existing microsomes.^[1] From the occurrence of microsomes and the characteristics of their enzymes, they can be regarded as a special type of lysosomes. from Phylogeny Historically, microsomes can be regarded as the remains of an ancient oxidative micro organ Biological evolution Gradually mitochondrion Replaced by. The micro body contains para long-chain fatty acids β Oxidative degradation Of Enzyme system , so can participate Lipid metabolism 。 Intracorpuscular catalase It can degrade H2O2 in cells to prevent Hydrogen oxide Causes cell poisoning. Catalase and L-2-hydroxy acid oxidase in the microbody can NADH Re oxidize and pass through the α- glycerol phosphoric acid dehydrogenase , support fructose Degradation. Therefore, microsomes and mitochondria are organelles that participate in cell respiration. Microbody and microsome （ microsome ）It is easy to confuse, but these are two completely different concepts. Microsomes are inherent organelles in cells, while microsomes are bound with a large number of ribosome The fragments of endoplasmic reticulum are tissues homogenate Ultracentrifugation After. Under pathological conditions, the number of microsomes in hepatocytes increased or decreased. Microbody increase can be caused by thyroid cord, so Hyperthyroidism In the liver cells of patients, the number of microsomes often increases; conversely, Hypothyroidism However, the number of microsomes in hepatocytes decreased. In addition, Chronic alcoholism and liver cancer The number of microsomes in hepatocytes was also increased, and its significance was not clear.

experimental study

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Hepatocyte: section 68 Pig liver , fixed by Bouin's solution, Paraffin section ， HE staining . Found under low power microscope polygon Of Hepatic lobule , select a hepatic lobule for high power microscopic observation, and we can see the hepatocytes arranged in a cord shape, which are polygonal and have 1-2 circles nucleus ， nucleolus Obviously, nuclear membrane Clear, in the nucleus Chromatin Sparse, slightly stained observation Organelle And Inclusion There are many kinds of organelles and inclusions, Experiment class Only the morphology and position of several main organelles and inclusions were observed under light microscope. All kinds of organelles and inclusions cannot be seen on ordinary HE stained sections, so special methods must be used to stain and display them. mitochondrion ——Teaching: film 3 Puppy pancreas , Regaud's solution fixation, paraffin section, Iron hematoxylin staining 。 Mitochondrial iron Hematoxylin It is black and distributed around the nucleus cytoplasm Under high power microscope, mitochondria are granular, linear or short rod shaped, straight or curved, with distinct outline. pancreas Of Secretory cell It is conical in shape, with a large and round nucleus in the center of the cell. Many large and round black granules are gathered at the free end of the cell as secretory granules. Golgi Complex - teaching: No. 2 film of dog or pig Spinal ganglia , Golgi's Arsenite silver nitrate French plating and dyeing. There are circular ridges of different sizes on the slice ganglion cells The nucleus is not stained, but yellowish nucleoli can be seen. In the cytoplasm around the nucleus, there are black coated reticular or granular substances, that is, under light microscope Golgi complex 。 Glycogen ——Teaching: No. 6 pig liver was fixed with cold Carnoy's solution, the glycogen was displayed by PAS reaction method, and the nucleus was stained with hematoxylin. Under the high power microscope, a large number of purple red glycogen particles or small pieces can be seen in the liver cells. In many liver cells, glycogen is biased to the side of the cell, which is caused by the preparation process and is distributed evenly in the living state.

Hepatocellular jaundice

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Hepatocellular jaundice It refers to the liver dysfunction In the blood caused by Increased bilirubin Caused by jaundice 。 To be specific, there are two reasons for hepatocyte jaundice: on the one hand, the liver cannot ingest and process normally Indirect bilirubin It leads to the increase of indirect bilirubin, while on the other hand, liver processing Direct bilirubin The inability to excrete into the biliary tract leads to the increase of direct bilirubin.

Hepatocellular jaundice severity

Hepatitis B patients How serious is hepatocellular jaundice? Hepatocellular jaundice often occurs in clinic, mostly in various hepatopathy as Viral hepatitis 、 cirrhosis , liver cancer and other causes such as Leptospirosis 、 septicemia Many patients do not know about hepatocellular jaundice seriousness 。 Hepatocellular jaundice is a kind of common jaundice, which is mainly caused by the damage of hepatocytes. But the liver can maintain human health It is very important. Once the liver cells become denatured and necrotic, it will do great harm to life, not to mention the patients with hepatitis B whose liver itself has been eroded. Therefore, the patients with hepatitis B must find out the cause actively Symptomatic treatment 。 Jaundice, as we often say, is divided into Hemolytic jaundice , hepatocellular jaundice Obstructive jaundice Three kinds, of which hepatocyte jaundice refers to jaundice caused by increased bilirubin in blood due to liver dysfunction. Hepatocellular jaundice is a very serious disease. Patients with hepatitis B accompanied with hepatocellular jaundice must be treated as soon as possible to avoid delayed treatment leading to liver necrosis and increasing the difficulty of treatment.

Symptoms of hepatocellular jaundice

To understand the symptoms and clinical manifestations of hepatocellular jaundice in order to personally understand its severity and harm to human body. It mainly includes: 1) The skin and sclera are light yellow to golden yellow, and the skin sometimes has itch 。 2) The manifestations of liver disease itself are as follows Acute hepatitis There may be fever , fatigue Tolerance 、 Hepatodynia Equal performance; Chronic liver disease There may be Liver palms 、 Spider nevus 、 Splenomegaly or ascites Etc. 3) Serum total bilirubin increased, especially conjugated bilirubin. 4) Urine bilirubin is positive, Urobilinogen The content of urobilinogen in feces can be normal or decreased.

Treatment of hepatocellular jaundice

since hepatitis B Patients with hepatocellular jaundice harmfulness Very big, then how to treat it? Experts pointed out that if you want to completely cure hepatocellular jaundice, you must treat both symptoms and root causes, which requires the fundamental treatment of hepatitis B. [

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