Sperm is divided into animal sperm and plant sperm.Male germ cell in sexual reproduction of animalsgerm cell, heterogamousMale gamete, bySpermatozoonHaploid germ cells produced.In life, sperm refers more to the mature male germ cellstestisFormed in.semenIt is an organic substance.Semen contains fructose and protein, as well as some enzymesinorganic saltandOrganic salt。
Normal semen is milky white or light yellow, and the number of sperm per milliliter of semen is generally 60 million to 200 million.Active sperm accounted for more than 60% of the total number.Misshapen spermIt shall be less than 10% of the total.Sperm motility lasts 3-4 hours at room temperature.
In 2010, the fifth edition of the latest WHO examination of human semen set the number of 15 million sperm per milliliter as normal.[1]
Plant sperm
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Basic Introduction
The morphology of plant sperm varies with plant species, including double flagellated sperm, multi flagellated sperm and non flagellated sperm.Primitive terrestrial bryophytes and lower vascular plants Lycopodium and Selaginella are generally double flagellate spermatozoa;Cycads and ginkgo in leeks, horsetails, true ferns and gymnosperms are multi flagellated spermatozoa.
Sperm (Plant) Algae bacteria plants, bryophytes, ferns, and cycads and ginkgoales in gymnosperms all have flagella and can swim sperm;However, in the gymnosperms, the spermatozoa of the order Pinaceae and Gnathophyta, as well as all angiosperms, do not have flagella.
Schematic Diagram of Plant Sperm Structure
External form
Each sperm has more than 100 flagella, while a spermatozoon of Zemi in Cycas has about 10-12 thousand flagella.The spermatozoa of cycads and ginkgo biloba are shaped like gyroscopes, and at the far end they are spirally banded, with a large number of flagella clustered on the spirals.The number of spiral bands is different: six in Zemi, five in Cycas, and three in Ginkgo.Spermatozoa of gymnosperms, such as conifers, Gnathophytes and angiosperms, do not have flagella.
In vascular plants, the largest sperm is a kind of cycads (Zemi) (Zamia chigua) with a diameter of about 400 microns.
internal structure
The internal structure of spermatozoa of various plant groups is very different.The zoosperms of lower plants are similar to those of animals in structure and development.For example, the spermatozoa of Callistonia spp. have two flagella, which grow in the front of the cell and extend to the rear.
The whole spermatozoon can be divided into three regions:
① The front end of the cell accounts for about 1/4, including a mass of mitochondria;
② There is a longer nucleus in the middle, accounting for about 1/2 of the cell;
③ The end also accounts for 1/4 and contains a mass of plastid.
In the study of sperm ultrastructure, the multi flagellated Zemi sperm is an example that has been studied in detail.The whole cell volume is mostly occupied by the nucleus, and the thin layer of cytoplasm is bound by the plasma membrane around the cell.Seen from the longitudinal section, the spiral band of sperm is ladder shaped.There is an electron dense cap like substance at the top of the front of the sperm.There are mitochondria, endoplasmic reticulum and other organelles in the cytoplasm.
Chinese scientist Zhu Cheng and others observed spermatocytes with tail structure in mature pollen grains of wheat.It has a blunt head at one end, mainly occupied by long oval nuclei;The other end is the tail of cytoplasm extension, and the end is gradually pointed, accounting for about 2/3 of the cell length.
In addition to mitochondria, endoplasmic reticulum, Golgi apparatus, ribosomes, small vacuoles and degenerated plastids, sperm cytoplasm also has microtubules and a large number of filaments parallel to the longitudinal axis of the cell.Mitochondria are concentrated in the cytoplasm of the tail.
Occurrence process
The number of spermatozoa produced by spermatozoon or male gametophyte of various plants varies greatly: one spermatozoon of Allium tuberosum can produce 4 spermatozoa, 128~256 Selaginella, thousands of Cynanchum pycnoides (thick cyst ferns), and hundreds of Lebai (thin cyst ferns);The male gametophyte of seed plants generally produces only two sperms.
Evolutionary trend
The general trend is from flagellated spermatozoa to non flagellated spermatocytes.The mode of sperm activity also changed from swimming by flagella to transporting sperm by pollen tube.For example, fertilization of lower vascular plants must be carried out under certain water conditions.This reflects the aquatic habits of algae to some extent.Cycas and ginkgo spermatozoa, while maintaining the flagellate characteristics of algae and lower vascular plants, have transited to pollen tube transport.In gymnosperms such as conifers and angiosperms, the movement of spermatozoa gets rid of the limitation of water conditions and is transported entirely by pollen tubes.
Sperm,sperm，spermatozoa。Since Leeuwenhoek observed the sperm of human beings and some higher animals in 1677, more than 1000 kinds of animal sperm have been studied so far, most of which are tadpole shaped.Since the 1950s, rapid progress has been made in understanding the biological characteristics of sperm.In mammals, for example, the structure of sperm can be divided into three parts: head, neck and tail.
headIt is mainly composed of nucleus and acrosome, which are round, long column, spiral, pear and axe shaped, and these shapes are determined by the shape of nucleus and acrosome.
The nuclei of mature spermatozoa contain highly dense chromatin, and it is difficult to distinguish its structure under light microscope and electron microscope.There is an acrosome at the front of the nucleus, which is a cap like structure composed of double membranes covering the first 2/3 of the nucleus. The layer near the plasma membrane is called the outer acrosome membrane, and the layer near the nucleus is called the inner acrosome membrane.There are particles of hydrolase in the acrosome, which are related to the sperm passing through various egg membranes outside the egg.The cavity between the acrosome and the nucleus is called the infraacrosome cavity, which contains actin.Some invertebrate sperm produce acrosome reaction during fertilization: actin polymerizes to form acrosome protuberances or acrosome filaments;The sperm can attach to the plasma membrane of the egg, leading to sperm egg fusion - fertilization.
Although the nuclear membrane is a double membrane structure, the distance between the two layers is very small, and there is only a nuclear membrane hole at the fold connecting the back end of the nucleus with the neck.
The discoverer of sperm: Leeuwenhoek
neckThis part is the shortest.Located behind the head, it is cylindrical or funnel-shaped, also known as the connecting segment.It is connected to the rear end of the core in the front and the tail in the rear.There is a base plate at the front end, which is composed of dense materials, and is just trapped in the depression called implantation nest at the rear end of the nucleus.There is a slightly thick head plate behind the base plate, and there is a transparent area between the two. The fine fibers in the head plate are connected to the nuclear membrane at the rear end of the nucleus through the base plate.Behind the head plate is the proximal centriole. Although it is slightly inclined, it is almost perpendicular to the axoneme formed by the distal centriole behind it.Around these structures, there are nine segmented columns composed of longitudinal fibers showing the depth and depth of the interval, and mitochondria are distributed around the periphery of the segmented columns.The nine segmented columns are closely connected with the head ends of the nine coarse fibers behind them.
tailIt is divided into three parts: middle section, main section and end section.The main structure is the axial wire running through the center.
middle partThe distance from the distal centriole to the ring is called the middle segment. Its length varies greatly in mammals, but its structure is generally similar.The main structure is axoneme and surrounding mitochondrial sheath.
① Axeme: The motor organ of sperm, which is formed by the distal centriole and extends to the end of sperm.The structure of sperm axoneme is similar to that of animal flagella (or cilia), which basically consists of 9+2 type, that is, the two microtubules in the center are single, and the nine microtubules in pairs (dyads) are around.
The fiber sheath outside the axoneme consists of 9 coarse fibers.They are connected to nine segmented columns in the neck.This is unique to mammalian sperm, so people classify mammalian sperm as 9+9+2 type (Figure 3), although its size and shape are different in various animals.Birds and some invertebrates have similar structures in their sperm.
② Mitochondrial sheath or mitochondrial spiral: mitochondria are connected with each other and spiral wrapped outside the coarse fiber, so it is called mitochondrial sheath.It is a continuous structure formed when mitochondria gather together and merge with each other during sperm formation.The number of turns of each mammalian spiral varies greatly, from ten to hundreds.
③ Ring: located at the rear end of the middle section.After the last circle of the linear granular sheath, the plasma membrane at that place turns inward.It is unique to mammalian spermatozoa and may be related to the prevention of mitochondrial retrogression during sperm movement.
Main sectionThe longest part of the tail consists of axoneme and tubular fiber sheath.There are two fiber processes in the fiber sheath forming longitudinal ridges. Because the longitudinal ridges are just located on the back and ventral sides, the sperm tail section is oval.
Last paragraphAs the main segment entered the terminal segment, the fiber sheath gradually became thinner and disappeared.
Atypical
The germ cells of male animals.Its shape is very different from that of ordinary cells.Spermatozoa of various animals can be divided into typical and atypical types. The typical type is generally tadpole shaped, with a nearly cylindrical head (different animals) and a slender tail, such as flagella.Atypical spermatozoa have various morphology but lack flagella.
An unexplained phenomenon is the production of so-called mutant sperm.In mammals (including humans), birds, amphibians, fish, insects and annelids, the same individual, not due to degeneration or pathological reasons, in addition to typical sperm, there are also variations of extra small, extra large, or even more than one flagellum.The shape of variant spermatozoa of marine and freshwater probranchia (molluscs) is completely different from that of normal spermatozoa.
The common feature is the lack of flagella, but their shapes are quite different.This kind of sperm is widely distributed in invertebrates.Some, such as the sperm of lower crustaceans, are spherical or banded, more like a cell than typical sperm.Some grow many thin and long protrusions, which may help to attach and prevent them from being washed away in the incubation chamber;The sperm of higher crustaceans has a complex shape. In addition to the slender protrusions, there are also chitin capsules.Atypical sperm of nematode animals are relatively simple like amoeba, while sperm of paraascaris equi has a unique lens.Because most of the atypical spermatozoa are simple in shape, it is easy to think that they stay in the early stage of sperm formation.It is generally believed that this simple shape is a secondary character from degeneration.
Standard human sperm
1. Semen volume: 2~6ml per ejaculation, but affected by the frequency and frequency of ejaculation.If the semen volume is less than 1ml/time, the semen volume is reduced; if the semen volume is more than 6ml/time, the semen volume is excessive. These are abnormal conditions.
2. Semen color: the color of normal semen is transparent and gray white. If abstinence lasts for a long time, it can be light yellow. If there is inflammation in the reproductive tract, it can be yellow, or even there is blood in semen.
3. Sperm density: sperm density refers to the number of sperm contained in each milliliter of semen. The normal number of sperm per milliliter of semen is more than 15 million. If less than 15 million/ml is oligospermia, it will affect fertility[1]。
4. Liquefaction time of semen: when semen is discharged from the body, it is in a gelatinous state. After 5 to 30 minutes, it will become liquid. This process is called liquefaction.Liquefaction of semen requires the participation of a series of proteolytic enzymes, which are viscous and non liquefied semen.It is common in patients with prostate or seminal vesicle diseases. Semen is weakly alkaline, with pH between 7.2 and 7.8. If pH<7, it is acidic, and if pH>8, it is alkaline, which will limit sperm function.
5. One hour survival rate of sperm: the percentage of motile sperm within one hour after ejaculation should not be less than 60%.
Sperm count
The semen was diluted quantitatively with the diluent (sodium bicarbonate in the diluent broke down the mucus to destroy the semen viscosity, and formaldehyde fixed the sperm), and then dropped into the blood cell counting pool for counting.It can also be reported clinically according to the total number of sperm discharged at one time. Normally, it is 39 × 10 according to the standard of the fifth editionsix。
The process from spermatogonia to spermatozoa is roughly similar in higher animals, which is carried out in the convoluted seminiferous tubules (seminiferous tubules) of the testis.Mammalian spermatogonia can proliferate as stem cells to produce new stem cells and differentiated cells;This not only preserves the generation of stem cells themselves, but also constantly generates differentiated cells from energy sources, which then generate primary spermatocytes.As for how many times they undergo mitosis to produce primary spermatocytes, all kinds of animals are different.In addition to the earliest spermatogonia, after each mitosis in the process of spermatogenesis, the cytoplasm is not completely separated, and the cells are connected by a bridge, which looks like syncytium.This may be conducive to maintaining strict synchronization between cells and producing a large number of sperm at the same time.
After the production of spermatocytes, they enter the growth phase and increase in size, which is called primary spermatocytes.Their nuclei synthesize DNA, and chromatin undergoes a series of complex changes in preparation for the first meiosis (see meiosis).After division, each primary spermatocyte produces two secondary spermatocytes with the same number of DNA as the somatic cells.The latter does not replicate DNA. After a relatively short stay, it enters the second mature division and forms two sperm cells.Therefore, a primary spermatocyte undergoes two maturation divisions to form four haploid sperm cells.Only this stage is generally similar in spermatogenesis of various animals.
Spermatogonia
The process from sperm cell to sperm is called spermatogenesis, also called sperm metamorphosis.This process is extremely complicated, mainly due to the sharp changes in the nucleus and organelles.The nucleoprotein composition in the nucleus changes significantly, leading to the densification of chromatin and the reduction of nuclear volume.In some animals, protamine replaces histones in the nucleus.Golgi apparatus, centriole and mitochondria also changed greatly.Golgi apparatus consists of a series of vesicles, some of which produce acrosome particles.The vesicles expanded and merged into larger vacuoles, covering the front end of the nucleus, and further evolved into a cap shaped acrosome.The particles in front of the acrosome also converge into larger acrosome particles showing mucopolysaccharide reaction.The centriole divides into two and moves away from each other while the Golgi apparatus changes. The proximal centriole is located in the depression at the rear end of the nucleus, and the distal centriole forms the flagellar axoneme and disappears later.Mitochondria are redistributed and form spirals around axoneme.This movement is related to the actin fibers around mitochondria.At the same time, most of the cytoplasm gathered to the neck and connected with the sperm only through a thin handle.At this time, the tail of the sperm has grown out from the back end. When the handle is broken, the sperm will break away from the cytoplasm (called the remnant) and enter the lumen of the seminiferous tubule.
The whole process of spermatogenesis is closely related to sertoli cells.The epithelium of seminiferous tubules is composed of long columnar supporting cells and germ cells with wide bottom and narrow top.Spermatocytes are located between the basement membrane of sertoli cells and convoluted seminiferous tubules, and there are desmosome connections between them (see intercellular connections).The spermatocytes that undergo maturation and division gradually move towards the lumen of the fine tubes, which is mainly due to the movement of the supporting cells themselves (possibly related to the rich microfilaments in them).Spermatocytes at all levels are located in the recess of sertoli cells, or the recess formed by two adjacent sertoli cells, and form gap connection with the cell membrane of sertoli cells, so as to connect.The spermatocytes at all levels are arranged according to the degree of maturity, and the spermatocytes in metamorphosis are closer to the top.Here, sertoli cells are connected with sperm cells through two structures: one is the junction structure formed by actin fibers in the ectoplasm;The other is globular zonal complex, which is formed by the top surface of supporting cells and the head surface of sperm cells.Because spermatocytes are constantly generated from spermatogonia for replacement, such precise arrangement is produced.
Hormonal regulation
Spermatogenesis is regulated by luteinizing hormone (LH) and follicle stimulating hormone (FSH) secreted by pituitary gland and testosterone secreted by leydig cells.Leydig cells, also known as Leydig cells, are located in the interstitial tissue between the convoluted seminiferous tubules. They synthesize and secrete testosterone into the convoluted seminiferous tubules to promote spermatogenesis.The production of testosterone is controlled by LH released by the pituitary gland.The FSH secreted by the pituitary stimulates the supporting cells to synthesize and secrete androgen binding proteins, which have strong affinity with testosterone to maintain the concentration of testosterone in the seminiferous tubules and maintain its role in spermatogenesis.In addition, FSH can directly initiate the division of spermatogonia and stimulate the development of early germ cells.
gene regulation
Normal human sperm
During spermatogenesis, chromatin is concentrated so that DNA cannot be transcribed, which is completed before the sperm is completely formed.The time at which transcription stops during spermatogenesis in various animals is not exactly the same.For example, in Drosophila melanogaster, RNA synthesis stops during the primary spermatocyte, while in mice, it is still going on in the sperm cell shortly after the mature division, and it will stop completely when the nucleus begins to elongate.
The formation of spermatozoa depends on protein synthesis. Since RNA synthesis has stopped, protein synthesis required for sperm metamorphosis must rely on stable RNA generated and stored earlier and not translated until sperm metamorphosis, which is a regulation at the post transcriptional level and a mechanism for delaying gene expression.
If protamine is synthesized in the cytoplasm of sperm and enters the nucleus to replace histone, its gene has been transcribed in the primary spermatocyte.The RNA synthesized in the nucleus is transferred to the cytoplasm and combines with the protein to form 16-18S nucleoprotein particles, which are stored in the cytoplasm in this form until the sperm cell stage.
In such cases where there is a long time interval between transcription and translation, the factors controlling post transcriptional gene expression are still poorly understood.Similar phenomena may also be encountered in the terminal differentiation of other types of cells.H19 and Igf2 genes are used to distinguish sperm from egg.Ensure that sperm does not combine with sperm and egg does not combine with egg.It is combination.
Sperm with deformed head
Sperm is a mature male germ cell, which is formed in the testis.The mature human sperm is like a tadpole, with a length of about 60 microns. It consists of a head containing parental genetic material and a tail with motor function. It is divided into four parts: head, neck, middle and tail.
Abnormal spermatozoa include morphological variation of head, body and tail, or mixed malformation of head and body.The head malformation includes giant head, head nucleus and cytoplasm inversion, mushroom like head and double head;Body deformities are large and thick, wedge-shaped, triangular, etc;The tail deformity includes thick tail, thick short, forked tail and double tail;The mixed malformations of head and body include enlargement of head and body, lengthening of nuclear malformation and mixed lengthening of head and body.
Sperm motility
sperm
There are several types of sperm movement, but the most common are two: one is direct forward movement, and the sperm actually swims forward;The second movement is swinging. The sperm only swings its tail, but does not move forward.
The movement types of epididymal sperm and ejaculatory sperm are different.The movement type of sperm in different components of ejaculate is also different.Because the speed of sperm movement is relatively high in the first part of ejaculate, artificial insemination is often carried out in the first part of ejaculate rich in sperm.When sperm encounters the changes of ion microenvironment and biophysical state of epididymal fluid, seminal plasma, cervical mucus, endometrial fluid, oviduct fluid and peritoneal fluid, the type of sperm movement also changes.In the presence of oviduct mucus and follicular fluid, sperm movement speed is accelerated.
The optimal proportion between prostate secretion and seminal vesicle secretion also affects sperm motility and motility.The secretory fluid of seminal vesicle contains several components that can damage the motility and vitality of sperm;Prostate secretion stimulates sperm movement.
Mixing kallikrein or kallikrein with semen samples can improve sperm motility.Regular administration of kallikrein to patients with few sperm for several months can increase the number of sperm in semen and improve the vitality of sperm.Only less than 100 of the hundreds of millions of sperm injected into the female reproductive tract at any one time can reach the fertilization site.
The sperm flagellum transmits sine waves repeatedly in a coordinated sequence.In this way, the energy generated in the flagellum can regulate the sperm movement.The flagellum consists of contractile proteins, coarse fibers, and microfilaments and microtubules associated with it.Therefore, in order to overcome the resistance of viscous cavity fluid such as cervical mucus, such driving force is needed for a long time.In order to move forward effectively, the sperm cell must coordinate the motion wave and maintain it as a result of the development process.
There are many contradictions about the three-dimensional spatial model of sperm tail movement, which may be because the photos taken are basically two-dimensional structures.However, the consensus is that there is a major wavy movement from the base to the tip on a plane, which is equivalent to the broad face of the sperm head;A rotating component attached to the moving wave causes a spiral motion.But it is not clear whether this rotating component is clockwise or counterclockwise.
When viewed from the base to the tip, the agglutination of human sperm head and head usually rotates counterclockwise, which is opposite to the direction of the forearm of the peripheral fibers of the axoneme.If the axoneme transmits a contraction pulse in some way, the impulse will pass through the axoneme in the same direction.
Adenosine triphosphate and adenosine triphosphate enzyme (ATPase), which play an important role in muscle contraction, are found in sperm, and they establish a connection between the bioenergy reaction and sperm movement.Just like ATP provides a lot of energy when muscle fibers contract, ATP decomposition provides a lot of energy for sperm fiber contraction.ATP consumed by spermatozoa can be supplemented by fructose glycolysis bioenergy reaction and respiration.
The metabolic process generates energy (ATP is its final form) and transmits it to structures that can transform chemical energy into mechanical kinetic energy.This energy supply is partly supplemented by the substrate metabolism of the medium, and partly generated by the in situ metabolic pathway, including adenosine triphosphate enzyme.The initiation of flagellar movement seems to depend partly on endocrine control through the second messenger cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP).However, in a series of reactions, the flagellar movement is mainly started by the calcium ion activated protein complex.
The bioelectric properties of sperm plasma membrane, together with neurochemical regulation and special ion-exchange enzyme system, that is, the activation of Na+and K+depends on magnesium ion ATPase, which may have a causal relationship with the coordination of motion waves and the movement speed of sperm cells.The speed of sperm movement may also be affected by the frequency of flagella movement.
Route of semen (sperm)[2]
Spermatogenesis, maturation and transportation are in human embryos, and primordial germ cells can be identified about the 24th day of development.At this time they appear in the yolk sac.The cells undergo mitosis and travel to the primordial gonad in the genital valley at the 4th to 5th week.The primordial germ cells increased rapidly through cell division during and after migration.On the 42nd day, up to 1300 primordial germ cells can be found in the undifferentiated gonads, and later they can become either oocytes or spermatogonia.At the early stage of differentiation, primordial germ cells were evenly distributed in the seminiferous tubules.They remain stationary throughout childhood, but in early puberty, spermatogonia begin to proliferate, become primary spermatocytes through mitosis, and begin meiosis until puberty.
Male adolescence is similar to female adolescence in many ways, but there are some obvious differences.The growth peak is measured by height, and the male occurs 2 years later.There is no precise time point similar to menarche to indicate that a certain stage of sexual maturity has been reached. Like female development, there can be great variation between individuals at a certain age.Testosterone causes physical growth and maturation of male accessory sex organs, as well as secondary sexual characteristics such as deep voice and characteristic distribution of hair.
The fully developed transverse section of the testes shows that the germ cells in the seminiferous tubules are at different stages of development.These cells come from the seminiferous epithelium and are wrapped by the basement membrane of seminiferous tubules.Leydig interstitial cells that produce and secrete the male hormone testosterone are located between the convoluted seminiferous tubules.Another specific cell, sertoli cell, is adjacent to germ cell in seminiferous tubule.These cells are not part of the germ cell line.They are located on the basement membrane of seminiferous tubules and extend into the human lumen, and branch into the middle of germ cells at different stages.For many years, it has been believed that sertoli cells only provide structural support in the testis.Now we know that they have many important functions.In adults, they play an important role in the release of sperm into the seminiferous tubules.They also provide an important barrier that separates the lumen from the rest of the convoluted seminiferous tubules that produce sperm, and they produce androgen binding proteins.Spermatogonia and adjacent sertoli cells were listed on the basement membrane.This acts as a functional barrier between the interstitial space and the fluid soaked in the reproductive epithelium.
Spermatogenesis is a series of processes from undifferentiated spermatogonia with 46 chromosomes (diploid, 2N) to spermatozoa with only 23 chromosomes (haploid, N).Throughout the life of adults, the testis constantly provides sperm, transports and stores it in the accessory reproductive organs.Evidence of normal spermatogenesis was seen in men in their 80s and 90s.This effective and continuous process provides incredible fertility.
In seminiferous tubules, spermatogonia undergo mitosis and eventually form spermatocytes.Adolescent primary spermatocytes undergo meiosis to form smaller secondary spermatocytes, which contain haploid chromosomes. Secondary spermatocytes further divide into the structure of spermatocytes.This division was not accompanied by a further reduction in the number of chromosomes.From spermatocyte to sperm is a mature process, neither meiosis nor mitosis.The final process is called spermatogenesis.Although nuclear division has been completed in primary spermatocyte and secondary spermatocyte stages, cytoplasmic division has not ended.The components of spermatocytes are still connected by cytoplasmic valley;Because sperm development is in contact with each other.
The number of sperm in the initial area of the epididymis is relatively small, and its concentration increases with the absorption of liquid by the epididymal epithelium.The tail of healthy young men was coiled tubules filled with sperm.Little is known about the environment of the distal part of the accessory halo, which allows sperm to store and maintain physiological integrity.In animals such as rabbits, sperm in the epididymis can maintain fertility for up to 30 days.
A series of changes have taken place in the process of sperm maturation in the epididymis.The sperm at the head of epididymis has no activity and shows abnormal swimming, and tends to move in a circular manner.When they pass through the epididymis, their swimming ability becomes unidirectional.The surface characteristics of sperm plasma membrane have undergone important changes, but no structural acrosome changes have been observed after human sperm maturation.
The penis is composed of three long columnar erectile tissues.It is surrounded by elastic sheath.Each cylinder contains blood vessels and convergence space that can be filled with blood flow during sexual arousal.
The two upper columnar bodies are called corpus cavernosum, which can harden the penis and increase the length and width of the penis when erecting.The cavernous body of the penis is divided into the penis foot at the root of the penis stem.The penis feet form attachment to the human body. When they are dispersed into healthy fibers, they are anatomically attached to the pelvis.
The third columnar body of the penis, the corpus cavernosum of the urethra, is located at the lower part of the penis.It ends at the glans.The urethra passes through the cavernous body of the urethra.When erecting, the cavernous body of the urethra is softer than that of the penis.During orgasm, the glans itself increases to almost twice its normal size.It is endowed with a large number of sensory nerve endings and has the strongest sense of sexual desire.
During orgasm, the penis hardens, the opening of the urethra expands, the testis partially rises, and the skin and tunica vaginalis of the halo pill increase.When the sexual excitement reaches the plateau stage, semen gathers in the prostate urethra, and there is an inevitable feeling of ejaculation.Cooper's gland at the root of the urethra (bulbar urethra gland) releases its contents.The testis increased in volume and turned forward, and the scrotum thickened.
During orgasm, the internal sphincter of the bladder muscle contracts, the seminal vesicle contracts, the vas deferens contracts, the erectile sphincter contracts, and the prostate contracts. These contraction forces force semen to pass through the urethra when the penis itself contracts.
Ejaculation involves the coordinated contraction of the epididymis and vas deferens, as well as the prostate and the smooth muscle of the seminal vesicle wall.At the distal end of the epididymis and vas deferens, the muscular layer of these duct walls is particularly thickened.The final result of stimulating contraction during orgasm is under the control of adrenergic nerve fibers.In contrast, erection depends on parasympathetic stimulation.Only the distal area with halo tail and vas deferens contracted significantly under the stimulation of adrenergic fibers of the hypogastric nerve.This type of nerve distribution prevents a large number of immature sperm from passing through the vas deferens and entering the seminal plasma during ejaculation.
The role of accessory sex organs is to receive semen from seminal vesicles, prostate and Cooper's gland (bulbar urethra gland) during ejaculation.
The seminal vesicles are paired structures located on the dorsal side of the bladder triangle.They secrete fructose rich products that enter the urethra through ejaculatory ducts.
The prostate surrounds the base of the urethra and sends its contents into the urethra through many small catheters during ejaculation.The prostate secretes a clear fluid, slightly acidic and rich in acid phosphatase.Citric acid, zinc and some proteolytic enzymes.
Secretions from the bulbar urethra gland, or Kuiper's gland, enter the bulbar urethra.They provide lubricant to keep the urethra moist.During orgasm of sexual excitement and complete erection, their contents can be released before ejaculation, sometimes with a small amount of sperm.Testicular androgen is known to maintain the function of accessory sexual organs.The main role of seminal vesicle and prostate secretion is to transport sperm during ejaculation, but it may also play a role in sperm metabolism.
Spermatogenesis
1. Spermatozoa are produced in the testes and take about 10 weeks to mature.
2. Mature sperm is stored in the epididymis.
3. Sperm is the smallest cell in the body, which needs balanced ability to supplement.
4. A normal adult male can produce 70 million to 150 million sperm every day.
5. Spermatozoa in the epididymis are transported through the vas deferens, where there is a fluid rich in fructose, which is equivalent to rocket fuel and helps sperm transport.
6. Most of the semen is alkaline, which helps sperm travel.
Sperm longevity
Although a man with normal sexual maturity ejects tens of millions or even as many as 200 million sperm at a time, most of these sperm lose their vitality and die in the acidic environment of the female reproductive tract.Generally speaking, the life span of sperm in the vagina does not exceed 8 hours, and only a small part of sperm escape and continue to move forward.When spermatozoa rush up to reach the uterine cavity, their number is only 1~5% when ejaculating. Why?Because the sperm left in the semen during ejaculation can be protected by a large amount of fructose and sugar decomposing enzymes in the semen. When the sperm enters the uterine cavity, it leaves the semen. Its living conditions are far inferior to those in the semen, so its life span is greatly shortened. The sperm with poor quality runs slowly, cannot reach the uterine cavity quickly, and loses vitality.After all the checkpoints, there are few sperm left that can finally reach the fertilized part of the fallopian tube.
However, as long as sperm enters the fallopian tube, it has a strong fertilization ability.Of course, only one or two sperm were lucky enough to combine with the egg, and the rest of the sperm died within 24 to 36 hours.Only the sperm stored in the cervical mucosal recess can live for 2 to 6 days.However, the ability of fertilization has been basically lost, because the fertilization ability of sperm can only last about 20 hours.
Data information
Semen volume per ejaculation: 1-2 teaspoons.
Average number of ejaculations in a man's life: 7200.
Average masturbation and ejaculation in a man's lifefrequency: 2000 times.
The average ejaculation volume of a man in his lifetime: (53 liters).
The sperm swung 1000 times forward 1 cm and swam 12 inches per hour.
Average ejaculation speed: 45 km/h VS average bus speed: 40.2 km/h.
Per teaspoon of semencalorieContent: 7 vs 150 calories per can.
Average length of penis without erection: 8.9cm (3.5 inches) vs after erectionPenisAverage length: 13 cm (5.1 inches)
The shortest penis in human history: 1.6 cm (5/8 inches) vs the longest penis in human history: 28 cm (11 inches).(The penis shrinks when bathing.)
The best way to enhance sexual competence:quit smokingExercise and lose weight.
The best food for improving sexual ability:Whole wheat、malt。
The proportion of American men who confess to masturbation: 60%
Proportion of confessing to masturbate at least once a day: 15%
ConfessMasturbationThe proportion of men who felt guilty afterwards: 78%
Ejaculation after ejaculation ranges from 5 minutes to 2 weeks.
Average number of erections per day for men: 11.
The average number of erections of men at night every day: 9 times.
The time required for sperm to swim to the egg: 2.5 seconds VS the time required for ordinary people to run a marathon: about 4 hours.
Life span of sperm: 2.5 months (from generation to ejaculation)
The smell of a man's semen is related to his dietAcidic food(Fish and meat) will produce sour smell like cheese or fishy smell, and dairy products will produce foul smell.It is said that the semen after eating asparagus tastes the most smelly, and acidic food and alcohol (except processed spirits) will produce a pleasant sweet taste.For example, orange, mango, kiwi, lemon, grapefruit, lime, drinking Corona beer and lime can double the effect.
Smells that stimulate blood flow to the penis: lavender, licorice, chocolate, donuts, and papaya pie (WesternThanksgivingEat often).
Growing place
The testis is the "birthplace" of sperm.There are three main types of cells in human testis:Sertoli cell、Interstitial cellandgerm cell。Sertoli cells and germ cells form seminiferous tubulesSeminiferous epitheliumInterstitial cells exist between convoluted seminiferous tubules.From the bottom to the top of the sertoli cells, the maturity of sperm cells is getting higher and higher.Distributed at the bottom isSpermatogoniaAnd the primary spermatocytes, secondary spermatocytes and spermatids are in the upper order.
After multiple mitosis and two meiosis (meiosis), a spermatogonia can form 256 sperm cells with only half of chromosomes, 50% of which containX chromosome, the other 50% containsY chromosome。
SpermatogoniaandSpermatocyteThe shape is round, without a tail, and the tail gradually appears when the sperm cells arrive.After a series of changes, the sperm cells finally mature, forming tadpole like sperm and discharging into the seminiferous tubules.The mature time of sperm in seminiferous tubules is about 64~72 days.
In addition, the epididymis will remain for about 19~25 days before further maturation, when the sperm has mobility and fertilization ability.Therefore, the whole process of sperm maturation takes about 90 days.This is what medication isAzoospermiaandoligospermia , which should last at least 3 months.Therefore, we must not be impatient. After taking the medicine for a few days, when we saw that there was no change in the number and activity rate of sperm, we immediately lost heart and changed to another medicine. In the end, we tried all kinds of medicine, but it did not work.
Functional structure
Structure of sperm
The sperm looks like a tadpole, with a total length of about 66μm, divided into two parts: head and tail.The head is oval on the front and pear shaped on the side, containing a very dense chromatinnucleusAnd aAcrosome。The acrosome is a kind of membranous organelle, which covers the front of the nucleus in a cap shape.The acrosome contains a variety of hydrolases, such asHyaluronidase, acrosin and acid phosphatase, equivalent tolysosome。The center of the tail contains an axoneme (similar to flagella) running through the whole tail, and the middle section contains spiral mitochondria.
The main function of sperm is forward movement and fertilization with eggs, so as to deliver genetic materialoocyteInside.During sexual intercourse, the semen is injected into the vagina, and the sperm flows out of the seminal plasma, passes through the cervix, uterine cavity, and isthmus of the fallopian tube, and finally reaches the ampulla of the fallopian tube to meet the oocyte.
The female reproductive tract is filled with viscous liquid, and the mucous membrane of the isthmus of the fallopian tube forms a zigzag fold, which poses a great resistance to sperm transportation and also plays a role in screening sperm. Only sperm with strong mobility and appropriate mobility can reach the position of the oocyte.
period of ovulationThe environment of the female reproductive tract also plays a role in regulating sperm function. Sperm also gain fertilization ability during transportation. The recess between the folds of the isthmus of the fallopian tube can temporarily store sperm and prevent the capacitated sperm from premature acrosome reaction.The fertilization ability of sperm can last for about one day in the female reproductive tract.
Sperm capacitation
It refers to a series of physiological changes through which sperm can obtain fertilization ability.The capacitation process begins when the sperm passes through the cervix.When reaching the isthmus of the fallopian tube, the capacitation process was nearly completed.In the later stage of capacitation, the spermatozoa are "hyperactivated", that is, there is a strong whip like movement, the swing amplitude of the head and tail is significantly increased, and the direction of movement becomes flexible, so that the sperm can pass through the isthmus of the fallopian tube.At the same time, the stability of the sperm cell membrane system is reduced, and some receptors on the cell membrane surface that are closely related to fertilization are exposed, which provides the conditions for interaction with oocytes and acrosome reaction.
Acrosome reaction is the structural and functional change of sperm after capacitation, which is similar to the exocytosis of somatic cells.When the sperm starts to undergo acrosome reaction, the acrosome first expands, the cell membrane of the sperm clings to the outer membrane of the acrosome, and multipoint fusion occurs. The fusion site breaks, and the acrosome communicates with the outside of the sperm through the break. The hydrolase in the contents of the acrosome is activated and diffuses out of the surface of the sperm head through the break, and the acrosome inner membrane is exposed.Acrosome reaction is the key change of sperm during fertilization. Only sperm that has completed acrosome reaction can fuse with oocyte to achieve fertilization.
Abnormal performance
1、azoospermiaNo sperm was found in the three semen introspections as azoospermia, and azoospermia can be divided into "acquired azoospermia" and "obstructive azoospermia";The latter refers to the testicle can produce sperm, but the vas deferens is blocked and can not discharge sperm.
2. Oligospermia: After 3-5 days of abstinence according to the latest World Health Organization definition in the fifth edition, the semen test concentration is less than 15 × 106/ml or the total number of ejaculated sperm per ejaculation is less than 39 × 106/ml, and other semen routine parameters are basically normal, which is called "oligospermia"[1]。
3. Abnormal sperm motility (asthenospermia): normal spermatozoa will move forward in a straight line actively, while abnormal spermatozoa will show no motility, poor motility, or sperm can only move or rotate in situ.The latest definition of the fifth edition of the World Health Organization is that after 3-5 days of abstinence, the proportion of forward motile sperm (PR)+non forward motile sperm (NP) in sperm is less than 40% or the proportion of forward motile sperm (PR) in sperm is less than 32% within 60 minutes, which is called asthenospermia[1]。
4. Sperm malformation: The fifth edition of the latest definition of the World Health Organization is that the normal sperm morphology rate is lower than 4%, which is considered as sperm malformation[1]。Abnormal spermatozoa include abnormal shape of head, body and tail, or mixed malformation of head and body.
5. Sperm agglutination: sperm agglutination is caused by the presence of sperm antibodies. Sperm agglutination is identified as sperm agglutination through sperm agglutination test and post coitus test, and must be differentiated from seminal vesicle liquefaction.
6. Spermatozoa: The survival rate of sperm in semen increases. Those who found more than 40% dead sperm in semen examination are called dead sperm disease, also known as dead sperm excess.However, due to improper inspection methods or failure to collect semen according to normal methods, the number of artificially formed dead sperm is increased, which is called suspended spermatozoosis and must be identified.
7. Semen non liquefaction disease: generally normal semen is just discharged from the body in the form of jelly, and then liquefied into flowing liquid after a certain period of time. If in vitro semen is still not liquefied or still contains liquefied clots at room temperature (22~25 ℃) for 60 minutes, it is called "semen non liquefaction disease", which affects sperm coagulation or braking, and slows or inhibits normal sperm movement.
Semen test data
Seven Taboos
1. Fear of smoking+drinking: smoking and excessive drinking are the enemies of sperm. The nicotine in cigarettes can not only reduce the secretion of sex hormones in men, but also have a direct killing ability to sperm.Long term heavy drinking, alcohol will make 70% of sperm dysplasia or loss of vitality.
The moment when the sperm penetrates into the egg
2. Fear of hunger: Some men are picky eaters and do not like to eat animal food. Over time, zinc content in the body will decrease.Zinc deficiency in men will reduce sexual desire and sexual function, and decrease the number of sperm.
3. Fear of heat: scrotum is testicular“Temperature regulator”。When the temperature is too low, the scrotum will shrink and close to the body;When the temperature is too high, the scrotum will relax and stay away from the body.The testis adapts to a temperature of 34 ℃. Only under normal conditions can the testis produce normal sperm.When testicular temperature exceeds 40 ℃, semen quality will be affected.If men have the habit of soaking in hot baths, steaming sauna and sitting for a long time, the sperm production will be reduced.
4. Fear of frequency: too frequent sexual intercourse will reduce the amount of sperm in ejaculation semen each time. If there are less than 20 million sperm per milliliter of semen, the chance of pregnancy will be very small.
5. Fear of worry: Because of family chores, the husband and wife are discord and blame each other, and both parties are in depression or trouble all day long, which can directly affect the nervous system and endocrine function of the body, causing testicular spermatogenesis disorder, leading to infertility.
6. Fear of drugs+X ray: some drugs have damage to sperm, such as furan drugs, hormones, etc., which can induce sperm growth disorders, sperm chromosome damage or breakage, and receiving large doses of radiation can cause sperm chromosome aberration.
7. Afraid of caffeine: many white-collar workers like to refresh themselves by drinking coffee. It should be noted that too much caffeine canSpermatogenic cellIt is a harmful substance. Drinking more than 4 cups of coffee every day will affect fertility. Men who are going to "create people" should avoid drinking a lot.Similarly, do not drink large quantities of cola and strong tea containing caffeine.
Related reports
Announce
edit
The research report of Japanese scientists said that in the process of sperm formation, some cells can "rejuvenate" and reverse to stem cells.The Institute of Basic Biology, a Japanese natural science research institution, issued a press release saying that Professor Yoshida Matsushi of the Institute and researcher Junde Nakagawa of Kyoto University jointly found that cells in the process of sperm formation can "rejuvenate" and become stem cells within a certain period of time.
In the 1970s, scientists proposed the "As model" of sperm formation.According to this model, the process of sperm formation is as follows: stem cells divide to produce two daughter cells with cytoplasm connected.As division continued, the number of daughter cells gradually increased to 4, 8, 16... It was previously believed that this process of division was irreversible, that is, the cells after division could not return to the stem cell state.The achievements of Yoshida Matsushi and others have corrected this wrong understanding.
In the study, scientists used green fluorescent protein to track the process of sperm formation.The results showed that while most cells formed sperm, a small number of cells returned to the original stem cell state.The papers of Japanese scientists have been published in the American journal Science.
How to improve sperm quality
According to the theory that the kidney stores essence in traditional Chinese medicine, it is necessary to take foods that can nourish the kidney and replenish essence, such as yam, eel, gingko, sea cucumber, frozen tofu, tofu skin, peanuts, walnuts, sesame, etc., to enhance the body's immunity and improve the ability to produce semen.This is coincident with the nutrition of western medicine. Western medicine believes that sufficient protein and vitamins can promote the production of sperm. Vitamin A, vitamin B and vitamin E can increase reproductive function. In addition, the absence of some trace elements, such as zinc, manganese, selenium, will also affect men's fertility.In addition, eating more green vegetables will help improve the quality of sperm, because green vegetables contain vitamin C, vitamin E, zinc, selenium and other ingredients that are conducive to sperm growth.Nuts and fish are rich in omega 3 fatty acids and should be eaten more, which are conducive to the growth of sperm cells.
Especially pay attention to the supplement of zinc. Animal food generally contains more zinc than vegetable food.Foods with more zinc include lean meat, liver, eggs, dairy products, cocoa, lotus seeds, peanuts, sesame seeds, walnuts, laver, kelp, shrimp, sea fish, red beans, lychees, chestnuts, melon seeds, almonds, celery, persimmons, etc.It is advisable to eat more soybean products such as coarse flour and tofu, beef, mutton, fish, lean meat, peanuts, sesame and dairy products.
In addition, there are many foods that are harmful to sperm. For example, raw cottonseed oil, tripterygium wilfordii (Chinese herbal medicine), and compound decoction such as Scrophulariae, Asparagus, water stone, phellodendron, and Scrophulariae will affect the spermatogenic function and reduce sperm vitality.People think that healthy and nutritious bean food contains abundant phytoestrogens. Overconsumption can cause endocrine disorder in the body, which may reduce the number and vitality of sperm.And the starch food of barbecue and deep frying contains the carcinogen acrylamide, which can lead to less men and weak sperm.
Zinc has an important impact on human body and sexual organ development. Zinc deficiency can cause growth retardation, low reproductive function, and then reduce sperm quality to induce infertility.To effectively improve the quality of sperm, you can often eat walnuts, peanuts, pine nuts and nuts rich in zinc in daily life.In addition, the study found that pumpkin seeds, white onions, ginger and other healthy foods also help to increase the number of sperm and improve sperm quality.
It is also one of the effective ways to improve sperm quality for weak men through proper physical exercise.Aerobic sports that are more conducive to men are: running, swimming, badminton, and combat gymnastics.At the same time, eating more fresh vegetables and fruits and paying attention to adding more vitamins can improve the quality of sperm.These sports are not only very helpful to improve the vitality of male sperm, but also can help relieve the pressure on work and release all kinds of bad emotions.
How to cultivate high-quality sperm
First: Keep away from alcohol and tobacco;
Second, we must keep the scrotum warm;
Third: Don't be too fat;
Fourth: abstinence, control the number of sexual intercourse;
Fifth, it is necessary to reasonably adjust the diet structure;
Sixth: We must keep clean;
Seventh: prevent magnetic and nuclear radiation;
Eighth: ensure good health
Ninth: Master your body's biological clock
quality analysis
1. Color:
Normal semen is gray or milky white.
Pale yellow is found in the patients with long ejaculation interval.
Brown red color can be seen in seminal vesicle inflammation, seminal vesicle tumor, prostatitis, and occasionally in urethral calculus.
Smell: A special fishy smell similar to carob tree or chestnut flower, which will change with food and living habits.
2. Liquefaction:
The ejaculated semen is thick jelly, which will liquefy after about 3~30 minutes and become thin liquid.
Non coagulation of semen can be seen in congenital bilateral absence of vas deferens and seminal vesicles.
Semen that does not liquefy for more than 30 minutes is found in patients with prostate and seminal vesicle diseases.
The increased semen viscosity can be seen in the abnormal secretion of the liquefying enzyme system of the prostate.
3. Semen volume:
Normal 2~6ml, average 3ml, less than 1ml or more than 8ml are abnormal
Decreased fluid volume can be seen in prostate and seminal vesicle lesions or reverse ejaculation
PH: normal PH is 7.0-7.8
Decrease of sperm activity and metabolism when semen is slightly acidic
The sperm motility increased when the semen was slightly alkaline, but decreased when the semen was too alkaline
Standards for semen analysis
Published by the World Health Organization (WHO) in 2010The fifth edition of WHO Laboratory Manual for Human Semen Examination and Treatment(WHO laboratory manual for the Examination and processing of human semenFIFTH EDITION)[1]。
Hemogenesis
Blood in semen is called blood sperm.The reasons for blood sperm:
(1) Inflammation of reproductive tract: such as prostatitis, seminal vesiculitis, urethritis, epididymitis, spermatic cord prostate stones, urinary bladder stones.
(2) Obstruction and cyst of seminal duct.
(3) Tumor and vascular abnormalities.
(4) Systemic factors: hypertension, hemophilia.
(5) Genital tract injury.
Judge the cause of sperm blood
The discharged semen is red in the back and milky in the front, which may be prostatitis, posterior urethritis or ejaculatory duct inflammation.If the semen discharged by male friends is all blood red, it is likely to be seminal vesiculitis.In addition, if the color of male blood sperm is bright red, it means proximal hemorrhage. If it is dark red blood, it is mostly related to inflammation.
Nutrition supplement
If the amount of sperm is small, it is asthenospermia and needs medication.There are many trace elements involved in male reproductive function, and the trace elements related to sperm production and maturation are mainly zinc, selenium, copper, cadmium, and zinc and selenium are the most important.When zinc and selenium are deficient, the hypothalamus pituitary gonad axis is affected, making the pituitary secretion of gonadotropin decrease, gonadal function decline, spermatogenesis decrease, and the activity of zinc containing substances in liquefied semen is affected, resulting in delayed semen liquefaction based on non liquefaction.Therefore, zinc and selenium supplementation is the key to low sperm quantity.In terms of diet, experts suggest that people should eat more products that can tonify the kidney, replenish essence, replenish qi, nourish blood, and produce essence, so as to improve the quality and vitality of sperm.
1. Calcium plays an important role in sperm movement, capacitation, maintenance of hyaluronidase activity and fertilization
If the body is short of calcium, it can slow the sperm movement and reduce the activity of sperm acrosin.Therefore, men should also pay attention to eating more keepsakes rich in calcium, such as milk, sweet almonds, undaria pinnatifida, sunfish, coriander, mushrooms, mustard, ribs soup, bean products, raisins, seaweed, shrimp skin, kelp, and golden needle vegetables.
2. Arginine is the main component of sperm first birth, and the ability of sperm activity should be improved
Keepsakes containing very much arginine include sea cucumber, sunflower seed, tofu skin, frozen tofu, eel, hazelnut, yam, cuttlefish and sesame, peanut kernel, loach and ginkgo, etc.
Since ancient times, sea cucumber has been regarded as a treasure for tonifying the kidney and essence, impotence and impotence.
3. In addition, sperm activity is related to the amount of fructose contained in the seminal vesicle
If the fructose content in semen is low, it is easy to cause sperm death.
Fructose is particularly abundant in honey and various fruits, such as pears, apples, grapes, pineapples, and sweet oranges, so attention should be paid to taking information.
The products recommended by traditional Chinese medicine for replenishing essence, tonifying kidney and filling essence, such as river shrimp, fish bladder, bird meat, beef, dog meat, medlar, walnuts and leeks, are also optional.
4. Eating foods containing magnesium
Magnesium can help regulate human heart activity, reduce blood pressure, prevent heart disease, and improve men's fertility.
It is suggested that men should have 2 bowls of oatmeal porridge with milk and 1 banana for breakfast.Foods with more magnesium include soybeans, potatoes, walnuts, oatmeal, macaroni, leafy vegetables and seafood.
5. Sperm contains a lot of trace element zinc, which plays an important role in maintaining the normal reproductive function of men
Because zinc is necessary for sperm metabolism and can enhance sperm vitality, it is necessary to eat more keepsakes containing very rich zinc, such as oysters, bran, animal liver, clams, shrimp, shellfish, walnut, milk, beans, lotus seeds, etc.
The content of zinc in oyster meat is the highest in the public, and attention is paid to the intake of nucleic acid and protein that helps sperm metabolism, and can improve sexual ability.However, the daily consumption of zinc must not exceed 15 micrograms, because excessive consumption of zinc will affect the role of other minerals in the body.120g lean meat contains 7.5 micrograms of zinc.
6. Eat more foods with high melanin content, such as black beans, black rice, black sesame, walnuts, black fungus, etc。Animal meat, eggs, bone marrow, black sesame, cherry, mulberry, yam, etc. also have different degrees of kidney tonifying effects.
