The process of sperm development and maturation, the six factors, and the role of the blood-testis barrier

> 64. **How ​​does sperm mature?**

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As the saying goes, "You reap what you sow," and the seed of life is male.

> Sperm. Where does sperm originate, and how does it mature? To answer this question...

To understand this topic, we need to start with the structure of the testes.

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The testes contain many seminiferous tubules, each containing numerous germ cells called spermatogonia.

> Cells. These are the "embryos" that produce mature sperm. During childhood, these cells are in a mixed state...

> They enter a dormant state of chaos, only "awakening" after reaching sexual maturity, and undergo multiple divisions.

> Divide to develop into primary spermatocytes, then divide into secondary spermatocytes, and finally...

After the second cell division, sperm cells are formed, and these cells continue to develop into sperm. Therefore, the testes...

The testicles are the "factory" that produces sperm. This process takes about 74 days and is also affected by factors such as sperm production.

> Regulation and control of a series of hormones secreted by the thalamus and pituitary gland.

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Adult testes have a tremendous sperm-producing capacity, averaging 100,000 sperm per gram of tissue per day.

A person can produce 10 million sperm cells, but sperm production gradually declines after age 40, although there are still [opportunities].

> A report of a 90-year-old still having the ability to produce sperm.

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After sperm formation, sperm are collected in the rete testis via the straight seminiferous tubules of the testes, and then...

The epididymal duct converges from 8 to 12 efferent ductules. The epididymal duct is tortuous and coiled, with a total length of...

The sperm can travel up to 5-6 meters before migrating into the vas deferens. Sperm from the testes travel to the epididymis...

Afterwards, the sperm typically remain in the epididymis for 19-25 days, gradually acquiring nutrients during the process.

> The maturation process of sperm involves acquiring motility and the ability to be fertilized. Sperm have...

The inherent maturation capacity means that maturation does not necessarily occur in the epididymis. In vitro culture...

Under certain conditions, sperm can also mature. However, if sperm that does not mature in the epididymis is used...

Using sperm for artificial insemination results in a high rate of embryo mortality and malformation. Therefore, the epididymis is not...

The epididymis is a simple container channel, and its normal function provides suitable conditions for sperm maturation.

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Once sperm matures, during ejaculation, the sperm travels 35-45 cm.

The long vas deferens reaches the swollen ampulla at its end, and finally ejaculates through the ejaculatory duct.

The semen is expelled from the body through the urethra. The amount of semen expelled each time is approximately 2-6 ml.

Each milliliter contains 100-200 million sperm; when there are fewer than 20 million sperm per milliliter, fertilization is unlikely.

The chances are significantly reduced, and when there are fewer than 4 million chances, fertilization becomes difficult.

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> 65. **Do you know the six things sperm fear?**

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Because sperm are inherently delicate and easily harmed by various "enemies," therefore, in

We must never be careless in our daily lives.

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First, avoid tobacco and alcohol. Smoking and excessive drinking are major enemies of sperm. Some men's bodies...

The body is quite sensitive to the toxins in cigarettes, especially the reproductive cells in the testes.

> Harmful effects. Nicotine in cigarettes can reduce sex hormone secretion and kill sperm. Australia

An Australian chemist says that once men quit smoking, their blood levels of sexual desire decrease.

Hormones will increase. A Hungarian medical doctor claims that smokers' semen contains...

> The number of sperm in the sample is less than in those who do not suckle, but the number of abnormal sperm is higher. For example, in adult males...

Smoking 30 cigarettes a day reduces sperm survival rate to only 40%, while increasing sperm abnormality rate.

> High. This shows that long-term heavy smoking is one of the important factors leading to infertility. Alcohol abuse...

> It will only lead to decreased gonadal function, inhibit sperm formation, and may also reduce sperm count by about 70%.

Poor development or loss of motility of right sperm cells can lead to chromosomal abnormalities in the sperm, thus causing...

> Can cause fetal malformations or developmental delays.

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The second fear is "hunger." Sperm growth requires a supply of nutrients. Some men's diets...

Monotonous diet, picky eating, and dislike of animal-based foods (such as meat, eggs, fish, and...)

Consuming dairy products (and similar foods) over a long period can decrease the body's zinc levels. The trace element zinc is...

Known as the "harmony element for couples," zinc deficiency in men can lead to decreased libido and sexual function, and reduced sperm count.

The number of offspring decreases by 30-40%, and may even cause a person to lose their fertility.

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The third thing they fear is "heat." Sperm development requires low temperatures, therefore the temperature inside the scrotum...

> At least 1-1.5°C lower than body temperature, and the temperature inside the testicles is even 0.5°C lower.

The temperature must be above 1℃, otherwise the sperm will die. Maintaining this physiological state is the function of the scrotum as a "warmer".

The scrotum acts as a "temperature regulator." When the temperature is too high, the scrotum expands to increase heat dissipation.

The surface area of ​​the scrotum is such that it wrinkles when cold to reduce heat dissipation, thus maintaining its scrotum's surface area.

The temperature inside the vagina is lower than inside the abdominal cavity. If a man has a habit of taking hot baths, it can make the vagina...

Increased scrotal temperature can reduce sperm count and lead to infertility; wearing tight-fitting jeans or similar clothing can also cause this.

Tight-fitting pants will constrict the scrotum, making it difficult for the scrotum to dissipate heat, and the local temperature of the testicles will also rise accordingly.

High levels of hormones are detrimental to sperm development. Modern medicine is using this principle to search for certain...

Raising the temperature of the scrotum or testicles to achieve sterilization is an effective family planning measure.

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> The fourth thing to avoid is "frequent" sexual activity. Excessive sexual activity can lead to impotence and also make each ejaculation more difficult.

The number of sperm in the semen decreases. If there are fewer than 20 million sperm per milliliter of semen, then...

The chances of getting pregnant are very slim, less than 4 million, making it almost impossible for a wife to conceive.

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Five things to fear: "medicine" and "radiation." Frequent use of sedatives, anti-tumor drugs, and chemotherapy drugs.

Bustanilides and hormonal drugs in medications can cause sperm growth disorders.

> Chromosomal damage and breakage; excessive radiation exposure can also cause sperm staining.

> Physical deformities. Therefore, men of reproductive age should avoid prolonged and excessive contact with [the material/material].

These types of harmful substances should not be used indiscriminately.

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The sixth fear is "worry." If family matters cause discord between husband and wife, leading to mutual blame, both parties will ultimately...

> Living in constant worry and anxiety. These negative mental states can directly affect one's spirit.

Disorders of the testicular spermatogenesis function due to systemic and endocrine dysfunction can also lead to infertility after marriage.

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> 66. **What is the blood-testis barrier?**

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The blood-testis barrier refers to the barrier that separates the circulatory system from the spermatogenic cells in the later stages of development.

> A mechanism that separates to protect the smooth progress of the spermatogenesis process.

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Sperm production occurs in the seminiferous tubules of the testes. The seminiferous epithelium...

Although Sertoli cells do not divide or proliferate during spermatogenesis, they are essential for ensuring spermatogenesis.

The smooth progress is of great significance. The supporting cells are long columnar, running along the walls of the convoluted seminiferous tubules.

> (Basement membrane) arrangement, with portions of the cell membranes of adjacent cells connected by a specialized junction

> Connect them together. This divides the fine tube into two parts, from the tube wall to the connection.

The part below the device is called the base chamber, and the part above the connecting device is called the near-lumen chamber.

Spermatogonia and some early-stage primary spermatocytes are embedded in Sertoli cells.

> Within the cytoplasmic pits of the basal chamber, where slightly mature spermatocytes and sperm cells develop.

The cells are embedded in the cytoplasm near the lumen. The connecting apparatus enters from the basal chamber.

The portal into the near-luminal chamber. When the primordial spermatogenic cells develop to a certain stage, the connection...

The device opens automatically, allowing spermatogenic cells to pass through and enter the near-lumen chamber, after which the connecting device closes itself.

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Supporting cells form a barrier between the tube wall and the lumen through their own junctions.

The continuous "fence" is connected by a "gate" that opens and closes at set times. (In the blood)

Various substances can easily pass through the basement membrane of the seminiferous tubules and enter the basal chamber.

However, one cannot indiscriminately and arbitrarily pass through this "fence" to enter the near-lumen chamber.

The supporting cells and their connecting structures link the circulatory system with later stages of development.

The spermatogenic cells are separated, acting as a barrier, and are therefore considered a major component of the blood-testis barrier.

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The blood-testis barrier is a protective mechanism that not only prevents large amounts of hormones from entering the bloodstream.

The protons can pass through the gaps in the seminiferous epithelium into the proximal tubular chamber, and can also prevent the proximal tubular chamber from being blocked.

> Androgen-binding protein (an essential substance for sperm development) leaks out of the cavity;

Furthermore, due to the presence of the blood-testis barrier, antigens from the seminiferous epithelium near the tubule core are blocked.

The substance is separated from the body's circulatory system, thus preventing the onset of autoimmune reactions.

> Spermatogenesis. In the later stages of spermatogenesis, the development of spermatogenic cells requires a suitable stable environment.

The blood-testis barrier selectively transmits various substances in the blood, providing a pathway for spermatogenic cells.

The development of the brain provides a favorable microenvironment. Hormones, drugs, toxins, etc. in the blood also...

They cannot directly enter the proximal chamber; some are blocked outside the blood-testis barrier, while others...

> It must be transported by supporting cells to reach spermatogenic cells. If the blood-testis barrier is breached...

If something goes wrong, the normal sperm production process will be disrupted, and sperm may not even be produced.