In the female and male body, the process of maturation of germ cells is ongoing. And if with the ladies everything in this regard is quite clear, then men remain a mystery. It is unlikely that anyone far from medicine seriously thought what spermatogenesis is. But to have a general idea would be nice to expand general knowledge and a better understanding of one's own physiology.
Definition
To start this impromptu excursion into biology and histology is better from a theoretical basis. So what is spermatogenesis? This is a process whose final product is sperm. All stages of it are controlled by hormones and the nervous system.
Each cycle lasts about ninety days. This is three times more than in women, but the germ cells also mature several orders of magnitude more. In each of these 90 days, one hundred million active sperm matures in the testes. The most comfortable temperature for this process is 34-35 degrees Celsius.
Spermatogenesis can be divided into three phases, or periods:
- proliferation;
- meiosis;
- spermiogenesis.
Periods
What is spermatogenesis? This is a sequential process that has stages and stages. Biologists distinguish four types of changes in tissues:
- reproduction of cells;
- height;
- ripening;
- the formation of ejaculate.
All this happens in the seminiferous tubules located inside the testicles. The outer layer of cells that form the walls of the tubules is spermatogonia. They continuously mitotically divide. This process begins before the birth of the child and lasts until twenty-five years. The cells divide so intensely that this period of time has been called the breeding season.
After puberty, spermatogonia is divided into two groups:
- those that continue to share;
- those who move to the center of the tubule, to the growth zone.
In a new place, the cells grow in size, they appear cytoplasm, rich in nutrients. From spermatogonia, they pass into spermatocytes of the first order. During this period of spermatogenesis, two daughter cells are formed from each spermatocyte, and spermatids are already obtained from them.
Then the spermatids are evenly distributed throughout the testis, lining it from the inside. And over time, they gradually mature to sperm, which enter the vas deferens, and then into the urethra.
Proliferation
Spermatogonia are located on the main membrane of the seminiferous tubules, the amount of which can reach a billion by the time of puberty. According to their morphological features, they are divided:
- on light cells of type A;
- dark cells of type A;
- cells of type B.
Dark spermatogonia are reserve, they are in an inert state until the moment when there is a need for them (after a serious illness or exposure). Light cells continuously mitotically divide, creating both A- and B-type cells.
As a result of spermatogenesis in the embryonic period and from the moment of birth to 14 years, a significant pool of cells that can differentiate into spermatozoa accumulate in men. This provides them with longer fertility than women (only 300 eggs and they do not divide).
Meiosis: spermatogenesis
Spermatogonia belonging to B-type cells are first divided several times by mitosis and turn into a first-order spermatocyte. This cell, in turn, also divides, but not evenly, but by meiosis. At the end of the first stage, two daughter cells are formed - second-order spermatocytes, each of which contains a half set of chromosomes. The second stage ends with the receipt of two spermatids from each spermatocyte.
In total, four new cells are obtained from one. Each of them has a haploid set of chromosomes and in the future may participate in the fertilization of the egg.
Spermiogenesis
The difference between spermatogenesis and oogenesis is that in the final you should get as many small cells containing genetic information as possible, and not one, but large and full of nutrients.
In order to make a sperm from a spermatocyte, he needs to undergo a number of serious morphological changes. Each spermatid is located next to the Sertoli cell, where it “matures”. First, the cell is rounded, then extended, and acrosomal granules appear in it. These inclusions are then collected at one of the poles of the cell, and the “acrosomal cap” is located there.
Mitochondria condense in the middle of the cell, it is they who will move the sperm cell forward. The cytoplasm continues to stretch and a tail forms. As soon as the cell has acquired its usual form, maturation is completed, and it takes its place on the inner surface of the spermatic cord.
Features of cell formation
What is spermatogenesis? Is a process whose main goal is the emergence of mature healthy germ cells with the right amount of genetic information. The entire process of the appearance of sperm from basal cells takes a month.
Specific enzymes are synthesized in male germ cells , which help to detect the egg, reach it, dissolve the protective membrane and form a zygote. They are concentrated in the very acrosomal cap, which was already discussed above.
Another feature of sperm is their motility. The egg moves from the ovary into the fallopian tube and further into the uterus only due to interaction with fimbriae, translational movement of the cilia and peristalsis of the tubes. The sperm cell has a tail, which acts as a flagellum and pushes the rest of the cell forward.
The quality and viability of sperm is affected by medication, alcohol, drugs and smoking, as well as other exogenous and endogenous factors.
Factors Affecting the Process
All germ cells and spermatogenesis are extremely sensitive to the effects of adverse factors. Violation of this process at some of its stages can lead to a decrease in fertility or infertility.
Despite the fact that everyone is accustomed to consider the stronger sex to be unshakable in terms of health, the male body is extremely sensitive to changes in body temperature and viral infections. Enough banal colds with slight hyperthermia to destroy plans for conceiving a baby for three months.
Therefore, men should follow basic recommendations for caring for their body in order to maintain reproductive function for a long time:
- in no case do not wear tight underwear, which can disrupt the blood flow and increase the temperature locally;
- Avoid frequent visits to the sauna and bath;
- take antibiotics, antiallergic and hormonal drugs with caution.
Some women, worried that they are unable to conceive, are trying to influence the male body to improve spermograms. To do this, you need to diversify your diet, abandon bad habits, avoid frequent medications, drink herbal tea instead of coffee, play sports and periodically go for massage sessions.
Additional methods of exposure to the body
Oogenesis and spermatogenesis can be enhanced artificially. For this, hormonal stimulation of partners is carried out in family medicine clinics. As a rule, such procedures are done for couples who decide to have a baby under the IVF (in vitro fertilization) program or ICSI (intracellular sperm injection).
However, such procedures are unsafe for both partners, and artificial stimulants inhibit the production of their own hormones and exacerbate infertility. Natural activation of spermatogenesis occurs in men who are in love. The brain synthesizes a wide variety of hormones that not only improve the quality and quantity of seminal fluid, but also strengthen the immune system, increase muscle tone and speed up metabolism.
Spermogram
In order to influence the reproduction and spermatogenesis, an analysis of the ejaculate is necessary. Such a detailed study allows you to determine the number of active sperm, their quality, to identify pathological changes at an early stage (if any).
Normally, the ejaculate is a white or grayish liquid with neutral acidity. One milliliter must contain at least 20 million sperm, and more than 25 percent of them must be motile. In addition, the proportion of normal cells suitable for fertilization should be at least half of the total. By the standards of the World Health Organization, about fifty percent of sperm must be alive and not have abnormalities in the morphological structure. An insignificant presence of leukocytes and round cells is allowed in seminal fluid . Red blood cells, macrophages, and amyloid bodies are not welcome.
There are such indicators of spermogram:
- normogram;
- oligospermia - a small amount of sperm;
- polyspermia - a lot of ejaculate;
- viscometry - excessive viscosity;
- oligozoospermia - few sperm;
- azoospermia - there are no sperm in the fluid;
- asthenozoospermia - immobility of morphologically unchanged spermatozoa.
There are other options, but these are the most common cases.