What hormones are gonadotropic? The importance of pituitary hormones for humans Gonadotropic hormones are.

Gonadotropic hormones include FSH (follicle-stimulating hormone), LTG (luteotropic hormone) and LH (luteinizing hormone).

These hormones affect the development and growth of follicles, function and formation corpus luteum in the ovaries. But on early stage follicle growth does not depend on gonadotropic hormones; it also occurs after hypophysectomy.

What is GnRH?

Gonadotropic releasing hormone (GnRH) is a first-order hypothalamic regulator of reproductive function. There are two types in humans (GnRH-1 and GnRH-2). Both of them are peptides consisting of 10 amino acids, their synthesis is encoded by different genes.

FSH is produced by small, round basophils located in the anterior lobe of the pituitary gland in peripheral areas. This hormone acts at the stage of presentation of a large oocyte from the egg, which is surrounded by several layers of granulosa. FSH promotes the proliferation of granulosa cells and the secretion of follicular fluid.

How are gonadotropic hormones formed?

Basophils, which are located in the anterior lobe, or rather in its central part, form LH. In women, this hormone promotes the transformation of the follicle into the corpus luteum and ovulation. And in men, this hormone stimulates the GSIC, interstitial cells.
LH and FSH are similar in chemical structure and physicochemical properties of hormones. Their ratio depends on the phase of the menstrual cycle during which they are secreted. Synergists in action, LH and FSH carry out almost all biological processes through joint secretion.

Gonadotropic hormones - what is known about them?

Basic functions of hormones

Prolactin or LTG is produced by the pituitary gland and its acidophiles. It affects the corpus luteum and supports its endocrine function. Affects milk production after childbirth. We can conclude that this hormone acts after preliminary stimulation of the target organs with LH and FSH. The secretion of FSH is suppressed by the hormone LTG, which can be associated with the absence of menstruation during breastfeeding.
During pregnancy, hCG, human chorionic gonadotropin, is formed in the placental tissue, which has an effect similar to LH, although it differs in structure from the pituitary gonadotropic hormones that are used in hormonal treatment

Biological action of gonadotropic hormones

The main effect of gonadotropic hormones can be called an indirect effect on the ovary by stimulating the secretion of its hormones, as a result of which a pituitary-ovarian cycle is created, with characteristic fluctuations in hormonal production.

The relationship between the activity of the ovary and the function of the pituitary gonadotropic gland plays an important role in the regulation menstrual cycle. A certain amount of pituitary gonadotropic hormones stimulates the hormone production of the ovary and causes an increase in the concentration of steroid hormones in the blood. It may also be noted that increased content ovarian hormones inhibit the secretion of the corresponding pituitary hormones. This is why gonadotropic hormones are interesting.

This interaction can be most clearly seen between LH and FSH, and progesterone and estrogen. FSH stimulates the secretion of estrogens, the development and growth of follicles, although the presence of LH is necessary for the full production of estrogens. A strong increase in estrogen levels during ovulation stimulates LH and stops FSH. The corpus luteum develops due to the action of LH and its secretory activity increases with the secretion of LTG. In this case, progesterone is formed, which suppresses the secretion of LH, and with reduced secretion of LH and FSH, menstruation begins. Menstruation and ovulation are the results of the pituitary-ovarian cycle, which is formed by cyclicity in the functions of the ovaries and pituitary gland.

Influence of age and cycle phase

Age and cycle phase affect the secretion of gonadotropic hormones. During menopause, when ovarian function ceases, the gonadotropic activity of the pituitary gland increases by more than five times. This is due to the fact that there is no inhibitory effect of steroid hormones. The secretion of FSH predominates.

Data about biological action There is very little LTG. It is believed that the LTG hormone stimulates biosynthetic processes and lactation, as well as protein biosynthesis in the mammary gland, accelerates the development and growth of the mammary glands.

Gonadotropic hormones - their metabolism

The metabolism of gonadotropic hormones has not been sufficiently studied. They circulate in the blood for quite a long time and are distributed in the serum differently: LH is concentrated in the fractions of b1-globulins and albumins, and FSH in the fractions of b2 and a1-globulins. All gonadotropins that are formed in the body are excreted in the urine. The gonadotropic hormones of the pituitary gland isolated from urine and blood are similar in their physicochemical properties, but the biological activity is higher for blood gonadotropins. Although there is no direct evidence, there is a possibility that hormone inactivation occurs in the liver.

Mechanism of action of hormones

Since it is known how hormones influence metabolism, research into the mechanism of hormonal action is of great interest. The variety of effects of hormones on the human body, especially the steroid series, is apparently possible due to the presence of a common mechanism of action on the cell.

Gonadotropic hormones are produced, as mentioned above, in the pituitary gland. The results of an experimental study of 3H and 125I labeled hormones showed the existence of a hormone recognition mechanism in the cells of target organs, through which the hormone accumulates in the cell.

Nowadays, the connection between the action of hormones on cells and highly specific protein molecules and receptors is considered to be proven. There are two types of reception - membrane reception (for hormones of a protein nature that practically do not penetrate the cell) and intracellular reception (for steroid hormones that penetrate into the cell relatively easily).

In the first case, the receptor apparatus is located in the cytoplasm of the cell and makes the action of the hormone possible, and in the second case it determines the formation of an intermediary. All hormones are associated with their specific receptors. Predominantly receptor proteins are located in the target organs of this hormone, but the great potential for the action of hormones, especially steroids, makes us think about the presence of receptors in other organs as well.

What happens in the first stage?

The basis of the first stage of the hormone’s influence on the cell can be called the formation of its bond with the protein and the hormone-receptor complex. This process occurs without the participation of enzymes and is reversible. The limited binding capacity of hormone receptors protects the cell from biological penetration active substances in excess.
The main point of action of steroid hormones is the cell nucleus. One can imagine a scheme in which the formed hormone-receptor complex penetrates the nucleus after transformation, which results in the synthesis of specific messenger RNA, on the matrix of which enzymatic specific proteins are synthesized in the cytoplasm, providing the action of hormones with their functions.

Peptide hormones, gonadotropins, begin their action by influencing the adenyl cyclase system embedded in the cell membrane. By acting on cells, pituitary hormones activate the enzyme adenyl cyclase, localized in the cell membrane, which is associated with a receptor unique to any hormone. This enzyme promotes the formation of cAMP (adenosine monophosphate) from ATP near the inner membrane surface in the cytoplasm. In combination with a subunit of the cAMP-protein kinase dependent enzyme, phosphorylation of a certain number of enzymes is activated: lipase B, phosphorylase B kinase and other proteins. Protein phosphorylation promotes the synthesis of proteins in polysomes and the breakdown of glycogen, etc.

What does the level of gonadotropic hormones affect?

Conclusions

It can be concluded that the action of gonadotropic hormones involves 2 types of receptor proteins: the cAMP receptor and membrane hormone receptors. Accordingly, cAMP can be called an intracellular mediator, which ensures the distribution of the influence of this hormone on enzyme systems.

That is, we can conclude that gonadotropic hormone is very important for humans. Drugs containing hormones of this type are increasingly used for various diseases of the endocrine system. They help restore the correct balance.

Affecting the development and function of the gonads. Gonadotropins include luteinizing, follicle-stimulating and lactogenic hormones of the anterior pituitary gland, as well as human chorionic gonadotropin, a hormone produced. Luteinizing hormone (and human chorionic gonadotropin, which has the same effect) stimulates ovulation and the formation of the corpus luteum in women, and the secretion of androgens by the testicle in men. Follicle-stimulating hormone promotes follicle maturation in women and spermatogenesis in men.

Chorionic gonadotropin (Gonadotropinum chorionicum) and serum gonadotropin (Gonadotropinum sericum) are used as gonadotropic hormone preparations. The action of the first is characterized by the predominance of the effects of luteinizing hormone, the action of the second is characterized by the predominance of the effects of follicle-stimulating hormone. Preparations of gonadotropic hormones are used alone or alternating with each other in women for menstrual irregularities and infertility, in men for hypofunction of the gonads. Chorionic gonadotropin is prescribed at 1000-2000 units, serum gonadotropin - at 3000 units. Administered intramuscularly. Treatment is carried out by a doctor according to a special scheme. Form of release of gonadotropins: ampoules of 500 and 1000 U. Store gonadotropin at a temperature not exceeding 20° in a place protected from light.

Choriogonical gonadotropin(Honadotropinum chorionicum). The drug is obtained from the urine of pregnant women. It is close in action to the luteinizing hormone of the anterior pituitary gland. In women, it promotes the formation, maturation and rupture of the follicle, the transformation of the corpus luteum, increasing its function and lengthening the time of its existence. In men, it stimulates the function of interstitial cells of the gonads and normalizes the development of the gonads with delayed sexual development.

The drug is produced in lyophilized form; its solutions are unstable, they are prepared as needed.

The drug is standardized biologically. Its activity is expressed in units of action (AU), 1 UNIT corresponds to the activity of 0.1 mg of standard choriogonic gonadotropin powder.

Indications. In women, absence and irregularities of the menstrual cycle caused by pituitary insufficiency. Habitual miscarriage. Prolongation of the menstrual cycle. Infertility of ovarian origin. Functional uterine bleeding, In men, to stimulate the intrasecretory function of the testicles, normalize the development of the gonads. In young men, cryptorchidism, eunuchoidism, delayed puberty due to hypofunction of the pituitary gland. Both sexes experience slow growth. Obesity. Bed-wetting.

Method of application. The drug solution is administered intramuscularly. For amenorrhea and infertility, administer 500-1000 units per day for a week (starting from the 14-16th day of the cycle) once a month or 1000-1500 units per day for 3-5 days (also starting from the middle of the cycle) once a month. Courses of treatment are repeated over several cycles.

In case of heavy and frequent menstruation, 1000-2000 units are prescribed to prolong the existence of the corpus luteum for 4-5 days before the expected menstruation. For other indications, doses are selected depending on the nature and severity of the disease within the range of 500-1500-2000 IU per injection.

For bedwetting, children are given 250-500 units 2-3 times a week.

For cryptorchidism, adults are administered 500 units 2-3 times a week for 6-8 weeks. If necessary, the course of treatment is repeated after 2-3 months.

For eunuchoidism, adults are administered 750-1500 units per day for 3-6 weeks, then reduce the dose to 500-1000 units; children are given 100-200-500 units per injection. In case of growth retardation, children are administered 500 units per week 2-3 times for 2-3 months.

Release form. Ampoules of 500, 1000, 1500 units, ampoules with solvent are added to them. Before use, open the ampoule with gonadotropin, inject the solvent into it through a needle, and draw the dissolved drug back into the syringe for administration. Stored in a place protected from light at a temperature not exceeding 20°.

Gonadotropic hormones are synthesized by the pituitary gland. These include FSH (follicle stimulating hormone) and LH (luteinizing hormone). Gonadotropic hormones affect human reproductive and sexual function (both men and women). Their synthesis occurs in the anterior lobe of the pituitary gland, and in addition to gonadotropic hormones, in this lobe of the gland a large number of other hormones are produced, the function of which is to control and stimulate all glands endocrine system present in the body.

The pituitary gland is an appendage of the brain that weighs only half a gram and has a size of about 1 cm, however, depending on the condition and functions that it must perform, the pituitary gland can change its size and volume. But in any case, the normal size of the pituitary gland varies around 1 cm.

GGs in the female body have a direct effect on the egg - they regulate ovulation, promote rupture of the follicle, increase the functionality of the corpus luteum, and also enhance the synthesis of other necessary hormones, participate in the attachment of the fertilized egg to the uterine walls and control the formation of the placenta.

But with all this, a hormonal imbalance or taking medications (analogs of gonadotropic hormones) during pregnancy can harm the embryo. Therefore, treatment with synthetic hormone analogues is prescribed to women with infertility, cycle disorders, reduced functionality of the egg, and so on. But after pregnancy occurs, these medications are stopped or their dosage is sharply reduced.

As for men, gonadotropic hormones contribute to the descent of the testicles into the scrotum (in boys), the development of secondary sexual characteristics, spermatogenesis, and also increased testosterone synthesis. Synthetic analogues of GG are prescribed to men for the treatment of infertility.

So, women have GG hormones:

• stimulate the work of the endocrine glands;
• influence conception;
• regulate the menstrual cycle;
• LH stimulates the development of the corpus luteum;
• FSH controls the process of follicle maturation.

In addition, gonadotropic hormone has an effect on the endometrium.

In the male body:

• FSH regulates sperm maturation;
• maintain androgen concentration at the required level;
• produce testosterone;
• enhance the activity of Leydig cells;
• regulate the functionality of the endocrine glands.

Structural features

It must be said that the biological activity of GG is ensured by their structure. The hormone consists of two subunits - the first has an identical structure with all GG, and the second is unique. Each subunit individually does not have any effect on the body, but when they are combined, processes in the body are actively influenced.

This compound affects not only the sexual and reproductive spheres of a person, but also affects almost all endocrine processes in the body.

Human chorionic gonadotropin

There is another hormone that, although it is a gonadotropic hormone, is not a product of any gland in the body. This is hCG - human chorionic gonadotropin. This hormone is synthesized by the membrane of the embryo, therefore, it can only be detected in the body of a pregnant woman. Already on the second day after conception, this hormone can be detected in a woman’s blood. The functions of human chorionic gonadotropin are to preserve the corpus luteum, which supports the vital activity of the fertilized egg until the placenta is formed.

Despite the fact that hCG can only be observed in the blood of pregnant women, it is sometimes detected in the blood of non-pregnant women and even in men. This is an alarming signal that indicates that there is a hormone-producing tumor in the body, and that it is this tumor that synthesizes this hormone.

Why does hormone imbalance occur?

Scientists do not fully understand the reasons for the decrease or increase in GG, however, they suggest that this problem may lie in a genetic predisposition. In addition, hormonal imbalances can cause various diseases endocrine system, venereal diseases, injuries to the genital organs, operations on the peritoneum; in women, hormonal imbalance can occur as a result of frequent abortions.

Uncontrolled intake can play a big role in hormone imbalance. oral contraceptives, poor nutrition, overweight, stress and other negative factors.

Diagnostic measures

Gonadotropic insufficiency is diagnosed and treated by a gynecologist, endocrinologist or reproductive specialist. In the female half of the population, insufficiency of gonadotropic hormones is accompanied by underdevelopment of the mammary glands and labia, insufficient sizes reproductive organs, amenorrhea.

The following methods are used for diagnosis:

• laboratory tests blood for hormones;
• Ultrasound of the uterus and ovaries;
• lpiogram;
• bone density examination;
• study of adequate tubal patency and husband's spermogram in order to exclude other factors causing infertility.

In men, gonadotropic insufficiency occurs with hypogonadism. Diagnosis is carried out to determine primary or secondary hypogonadism. For this purpose, laboratory blood tests are performed.

Treatment in women

Therapeutic measures for the treatment of infertility due to hormonal deficiency are carried out in 2 stages - preparatory and ovulatory. During the preparatory stage, the woman is prescribed therapy with synthetic hormone analogues in order to increase the size of the uterus, improve the condition of the endometrium and stimulate the activity of the receptor apparatus. The duration of such therapy most often ranges from 3 months to a year.

After the preparatory period, ovulation induction begins; for this purpose, a drug from the menotropin group is selected; after ovulation has successfully completed, the luteal phase of the cycle is supported with Progesterone and Dydrogesterone.

The effectiveness of that treatment regimen, of course, depends on the degree of hormonal deficiency, on the correctness of therapy in the preparatory period and on the age of the patient. If gonadotropic insufficiency has developed in the pituitary form, then in most women this therapy gives positive results. If the deficiency has developed in the hypothalamic form, then the effectiveness is somewhat lower.

Treatment in men

The hormone (gonadotropin) in men causes a rather rare but extremely unpleasant disease - hypogonadism. The symptoms of this disease directly depend on how pronounced the gonadotropin deficiency is. The disease manifests itself in underdevelopment of the genital organs and weak expression of secondary sexual characteristics.

Treatment of hypogonadism consists of hormone replacement therapy, as a result of which the level of testosterone in the blood increases and the concentration of estrogen decreases. In some cases, this therapy is temporary, while in others, hormones are prescribed for lifelong use.

Upon appointment hormonal drugs, it is necessary to remember that hormones (gonadotropin and testosterone analogues) are prohibited during oncological processes in the body, in addition, taking these hormones is not recommended for prostatitis.

Three gonadotropic hormones were extracted from the anterior lobe of the pituitary gland: follicle-stimulating hormone (FSH), luteinizing hormone (LH) and luteotropic hormone (LTG).

All three hormones affect the ovary - the growth and development of follicles, the formation and function of the corpus luteum. However, follicular growth at the earliest stage does not depend on gonadotropic hormones and occurs even after hypophysectomy.

FSH is formed by small round basophils located in the peripheral areas of the anterior lobe. This hormone acts at the stage when the egg is a large oocyte surrounded by several layers of granulosa. FSH causes proliferation of granulosa cells and secretion of follicular fluid.

LH is formed by basophils located in the central part of the anterior lobe. In women, this hormone promotes ovulation and the transformation of the follicle into the corpus luteum. In men, it is interstitial cell stimulating hormone (ICSH).

Both hormones - FSH and LH are close to each other in chemical structure and physicochemical properties. They are secreted during the menstrual cycle, and their ratio varies depending on its phase. In terms of their action, FSH and LH are synergistic, and almost all biological effects are achieved through their joint secretion.

LTG, or prolactin, is produced by acidophilus of the pituitary gland. This hormone acts on the corpus luteum, supporting its endocrine function. After childbirth, it affects milk secretion. Consequently, the action of this hormone occurs after preliminary stimulation of the target organs with FSH and LH. LTG suppresses the secretion of FSH, which is associated with the absence of menstruation during breastfeeding.

During pregnancy, human chorionic gonadotropin (CG) is formed in the placental tissue, which, although different in structure from the pituitary gonadotropins, has a biological effect similar to LH, which is used in hormonal therapy.

Biological action of gonadotropic hormones. The main effect of gonadotropic hormones on the ovary is indirect, through stimulation of the secretion of its hormones, thereby creating a pituitary-ovarian cycle with a characteristic fluctuation in hormonal production.

There is a relationship between the gonadotropic function of the pituitary gland and the activity of the ovary, which plays a major role in the regulation of the menstrual cycle. Not large number gonadotropic hormones of the pituitary gland have a stimulating effect on the hormone production of the ovary, causing an increase in the concentration of steroid hormones in the blood. On the other hand, a significant increase in the content of ovarian hormones inhibits the secretion of the corresponding pituitary hormones.

This interaction is especially clearly seen between FSH and LH, on the one hand, and estrogens and progesterone, on the other. The growth and development of follicles, as well as the secretion of estrogens, are stimulated by FSH, although the presence of LH is also necessary for the full production of estrogens. A significant increase in estrogens during ovulation inhibits the secretion of FSH and stimulates LH, under the influence of which the corpus luteum develops, the secretory activity of the latter is enhanced by the secretion of LTG. The resulting progesterone, in turn, suppresses the secretion of LH, and with reduced secretion of FSH and LH, menstruation occurs. This cyclicity in the function of the pituitary gland and ovaries constitutes the pituitary-ovarian cycle, which results in ovulation and menstruation.

The secretion of gonadotropic hormones depends not only on the phase of the cycle, but also on age. With the cessation of ovarian function during menopause, the gonadotropic activity of the pituitary gland increases more than 5 times, which is due to the lack of the inhibitory effect of steroid hormones. In this case, FSH secretion predominates.

Data on the biological effects of LTG are very scarce. It is believed that LTG accelerates the growth and development of the mammary glands, stimulates lactation and biosynthetic processes, including protein biosynthesis in the mammary gland.

Metabolism of gonadotropic hormones. The metabolism of gonadotropic hormones has not been studied enough. They circulate in the blood for a relatively long time, being distributed unequally in the serum: FSH is concentrated in the fractions of a1- and b2-globulins, and LH is concentrated in the fractions of albumin and b1-globulins. All gonadotropins produced in the body are excreted in the urine. Despite the similarities physical and chemical properties gonadotropic hormones isolated from blood and urine; the biological activity of blood gonadotropins is much higher than that of urine. It is likely that hormone inactivation occurs in the liver, although direct evidence for this is not available.

Mechanism of action of hormones. Studying the mechanism of action of hormones is of great interest, since the influence of hormones on many aspects of metabolism is known. This diversity in the action of hormones, especially the steroid series, on the body is apparently possible if there are common mechanisms of their action on the cell.

The results of experimental studies with 3H and 125I labeled hormones showed that in the cells of target organs there is a mechanism of “recognition” of the hormone, due to which the hormone accumulates in a particular cell. At present, it can be considered proven that the effect of hormones on the cell is associated with highly specific protein molecules - receptors. There are two types of reception - for steroid hormones, which relatively easily penetrate into the cell (intracellular reception), and for hormones of a protein nature, which almost do not penetrate into the cell (membrane reception). In the first case, the receptor apparatus is located in the cytoplasm of the cell and determines the action of the hormone itself; in the second, it ensures the formation of an intermediary. Each hormone binds to its specific receptor. Receptor proteins are predominantly localized in the target organs for a given hormone, but the wide spectrum of action of hormones, especially steroids, suggests the presence of receptors in other organs.

The first stage of the hormone’s action on the cell is based on its binding to protein and the formation of a hormone-receptor complex. This process is reversible and occurs without the participation of enzymes. The receptors have a limited binding ability to hormones, which prevents the cell from penetrating excess biologically active substances.

The main point of application of the action of steroid hormones is the cell nucleus. Schematically, one can imagine that the formed hormone-receptor complex, after some transformation, penetrates into the nucleus, as a result of which specific messenger RNA is synthesized; on its matrix in the cytoplasm of cells, specific enzymatic proteins are synthesized, the functions of which ensure the action of hormones.

The action of peptide hormones, which include gonadotropins, begins with their influence on the adenyl cyclase system, “built in” into the cell membrane. Pituitary hormones, acting on cells, activate an enzyme localized in the cell membrane (adenyl cyclase), associated with a receptor specific to each hormone. This enzyme promotes the formation of cyclic 31, 5!-adenosine monophosphate (cAMP) from ATP in the cytoplasm at the inner membrane surface. The resulting cAMP in complex with the receptor, which is a subunit of the enzyme cAMP-dependent protein kinase, activates the phosphorylation of a number of enzymes (phosphorylase B kinase, lipase B) and other proteins. Phosphorylation of proteins stimulates the breakdown of glycogen and the synthesis of proteins in IT polysomes. d.

Thus, the mechanism of action of gonadotropic hormones includes two types of receptor proteins: membrane hormone receptors and the cAMP receptor. Consequently, cAMP turns out to be an intracellular mediator, ensuring the transmission of the hormone’s influence on enzymatic systems.

Gonadotropic hormones synthesized in the anterior lobe of the pituitary gland. In general, the hormones of the anterior pituitary gland control and stimulate all the endocrine glands of the body. The pituitary gland is stimulated by neurohormones of the pineal gland and hypothalamus. Let's consider the effect of gonadotropic hormones on the reproductive (genital) organs of the female body.

Follicle stimulating hormone of the pituitary gland(FSH)promotes follicle maturation and follicular production. Luteinizing hormone (LH) stimulates the development of the corpus luteum, and luteotropic hormone LTG(prolactin, mammotropin) - secretion of the corpus luteum hormone (). FSH and LH are synthesized in the anterior lobe of the pituitary gland simultaneously, but in different ratios: in the first half of the cycle, FSH predominates, in the second - LH, as well as LTG.

Gonadotropic hormones of the pituitary gland influence the endometrium through the ovary. Hormones of the follicle and corpus luteum, formed under the influence of gonadotropic hormones of the pituitary gland, cause (follicular hormone - proliferation, hormone of the corpus luteum - secretion). Gonadotropic hormones do not have a direct effect on the endometrium.

Between the anterior lobe of the pituitary gland and the ovaries there is not a one-way connection, but a complex interaction carried out through the hypothalamus. The pituitary gland, which stimulates ovarian function, is in turn influenced (via the hypothalamus) by the hormones of the follicle and corpus luteum.

Increasing production of follicular hormone (in the maturing follicle) interferes with the secretion of follicle-stimulating hormone (FSH) from the pituitary gland. At the same time, the secretion of luteinizing hormone (LH), necessary for ovulation and, further, for the development of the corpus luteum, increases. The increasing secretion of the corpus luteum hormone delays the formation of LH. A decrease in the secretion of this hormone leads to increased secretion of FSH, and therefore a new cycle begins in the ovary.

Thus, there is an increase in the secretion of either FSH or LH: periodic changes in gonadotropic hormones, in turn, cause.

The interaction between pituitary and ovarian hormones occurs through nervous system, especially with the help of autonomic centers located in the hypothalamic region.

During pregnancy, a new powerful source of secretion of gonadotropic hormones—the chorion—emerges in a woman’s body. Already in the first weeks of pregnancy, a large amount of chorionic gonadotropin is formed in it, which has a luteinizing effect. After the formation of the placenta, gonadotropic hormone is formed in the epithelial cover of the villi (in the cytotrophoblast). Human chorionic gonadotropin enters the bloodstream of the pregnant woman and is excreted in the urine. Methods for early diagnosis of pregnancy are based on this property of urine of pregnant women. After the fourth month of pregnancy, the gonadotropic activity of the placenta decreases. After childbirth, the release of gonadotropic hormones drops sharply and after 10-15 days they are not detectable in the urine.