In the female and male body, the process of maturation of germ cells is continuously going on. And if with the ladies everything in this regard is quite clear, then the men remain a mystery. It is unlikely that anyone far from medicine seriously thought about what spermatogenesis is. But having a general idea would be good for expanding general knowledge and better understanding of one's own physiology.
Definition
It is better to start this impromptu excursion into biology and histology from a theoretical base. So what is spermatogenesis? This is a process whose end product is spermatozoa. 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 germ cells also mature by several orders of magnitude. In each hour of those 90 days, one hundred million active spermatozoa mature in the testicles. The most comfortable temperature for this process is 34-35 degrees Celsius.
Spermatogenesis can be conditionally divided into three phases, or periods:
- proliferation;
- meiosis;- spermiogenesis.
Periods
What is spermatogenesis? This isa sequential process that has steps and stages. Biologists distinguish four types of tissue changes:
- cell reproduction;
- growth;
- maturation;- ejaculate formation.
It all happens in the seminiferous tubules, located inside the testicles. The outer layer of cells that form the walls of the tubules are spermogony. They are constantly mitotically dividing. This process begins before the birth of a child and continues until the age of twenty-five. Cells divide so rapidly that this period of time is called the reproduction period.
After puberty, spermatogonia are divided into two groups:
- those who continue to divide;- those who move to the center of the tubule, to the growth zone.
In a new place, cells increase in size, they have a 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 over the testis, lining it from the inside. And over time, they gradually mature into spermatozoa, which enter the vas deferens, and then into the urethra.
Proliferation
Spermatogonia are located on the main membrane of the seminiferous tubules, the number of which by the time of puberty can reach a billion. According to their morphological features, they are divided:
- on light type cellsA;
- dark type A cells;- type B cells.
Dark spermatogonia are reserve, they are in an inert state until the moment when they are needed (after a serious illness or radiation exposure). Light cells are continuously mitotically dividing, 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, men accumulate a significant pool of cells capable of differentiating into spermatozoa. This provides them with longer fertility than women (there are only 300 eggs and they do not divide).
Meiosis: spermatogenesis
Spermatogonia belonging to B-type cells first divide 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 - spermatocytes of the second order, each of which contains a half set of chromosomes. The second stage ends with the production 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 the final result should be as many small cells as possible containing genetic information, and not one, but large and full of nutrients.
Toa spermatozoon has turned out from a spermatocyte, it needs to undergo a series of serious morphological changes. Each spermatid is located next to the Sertoli cell, where it "matures". First, the cell is rounded, then stretched, 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, they will move the sperm forward. The cytoplasm continues to elongate and a tail is formed. As soon as the cell has acquired its usual appearance, maturation is completed, and it takes its place on the inner surface of the spermatic cord.
Features of cell formation
What is spermatogenesis? - This is a process whose main goal is the emergence of mature he althy germ cells with the right amount of genetic information. The whole process of emergence of spermatozoa from basal cells takes a month.
Specific enzymes are synthesized in the male germ cells that help to detect the egg, get to it, dissolve the protective shell and form a zygote. They are concentrated in the same acrosomal cap, which has already been discussed above.
Another feature of spermatozoa is their mobility. The egg moves from the ovary into the fallopian tube and further into the uterus only due to interaction with the fimbriae, the translational movement of the cilia and the peristalsis of the tubes. The spermatozoon, on the other hand, has a tail, which plays the role of a flagellum and pushes the restpart of the cell forward.
The quality and viability of spermatozoa is affected by medication, alcohol, drugs and tobacco use, as well as other exogenous and endogenous factors.
Factors influencing the process
All sex cells and spermatogenesis are extremely sensitive to the effects of adverse factors. Violation of this process at any of its stages can lead to reduced fertility or infertility.
Despite the fact that everyone is used to considering the stronger sex unshakable in terms of he alth, the male body is extremely sensitive to changes in body temperature and viral infections. A common cold with a slight hyperthermia is enough to ruin plans for conceiving a child for three months.
Therefore, men should follow the basic recommendations for caring for their body in order to maintain childbearing function for a long time:
- in no case should you wear tight underwear that can disrupt blood flow and locally increase the temperature;
- avoid frequent visits to the sauna and bath;- take antibiotics, anti-allergic and hormonal drugs.
Some women, worried that they are not able to conceive, try to influence the male body to improve the spermogram. To do this, you need to diversify your diet, give up bad habits, avoid frequent medications, drink herbal tea instead of coffee, play sports and periodically go for massages.
Additional methods of influencingorganism
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 those couples who have decided to have a child under the IVF (in vitro fertilization) or ICSI (intracellular sperm injection) program.
However, such procedures are not safe for both partners, and artificial stimulants inhibit the production of their own hormones and aggravate infertility. The 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 reproduction and spermatogenesis, it is necessary to analyze the ejaculate. Such a detailed study allows you to determine the number of active spermatozoa, their quality, to identify pathological changes at an early stage (if any).
Normally, ejaculate is a white or grayish liquid with a 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. According to the standards of the World He alth Organization, about fifty percent of spermatozoa must be alive and not have abnormalities in the morphological structure. Allowed in seminal fluidinsignificant presence of leukocytes and round cells. Red blood cells, macrophages and amyloid bodies are not welcome.
The following spermogram indicators are distinguished:
- normogram;
- oligospermia - small volume of sperm;
- polyspermia - a lot of ejaculate;
- viscosipathia - excessive viscosity;
- oligozoospermia - few spermatozoa;
- azoospermia - no spermatozoa in the liquid;- asthenozoospermia - immobility of morphologically unchanged spermatozoa.
There are other options, but these are the most common cases.
