Hormonal Control of Sexual Development

Hormonal Control of Sexual Development in Man
During embryonic development, the testicles begin to secrete a small amount of male hormone testosterone. The presence of this hormone in the embryo is very important for differentiation of male specific structures. Production remains low until puberty and no sperm cells are produced. Factors leading to the onset of adolescence are not fully known. One possibility is to reduce the sensitivity of the hypothalamus (which is very sensitive to testosterone in childhood and is inhibited even with low levels of the hormone) and start sending more gonadotropic-releasing hormone (GnRH) to the anterior pituitary, a gonadotropic hormone, luteinizing hormone (LH) and follicle-stimulating hormone ( FSH) is a warning to secrete.
LH stimulates the interstitial cells of the testes to produce more testosterone. Testosterone, together with FSH, allows maturation of seminiferous tubules and stimulates them to begin sperm production (spermatogenesis). Long-term preservation of spermatogenesis requires a continuous presence of testosterone (and its stimulating LH) and FSH. Testosterone once stimulates maturation of the assisted reproductive structures when it is present in the system in sufficient quantities, and at the same time normally initiates changes in secondary sexual properties such as the formation of beard and pubic hairs, thickening of the voice, formation of wider and stronger muscles, etc., which are associated with adolescence. If the testicles are to be removed by castration prior to puberty, these changes in the secondary sexual properties never occur. If castration is done after puberty, there is some regression in adult sexual characteristics; but they are not completely lost. After puberty, castration eliminates sexual desire in many animals.
This reluctance does not occur in people where psychological factors are more important than other animals. It is mostly confused with a surgical intervention, vasectomy and sometimes castration. In this small operation, the law is stopped by deferensia and the sperms are prevented from entering the urethra. Vasectomy does not lead to a regression in sexual characters; because there is no change in hormone levels.

Hormonal Control of Sexual Development in Female

As with the male, female adolescence is thought to begin with the release of more GnRH in the hypothalamus to lower the level of low sex hormone in the childhood and to stimulate the prehitu- tivity and secrete the secretion of FSH and LH. These gonadotropic hormones provide the maturation of the ovaries and they begin to secrete the female sex hormones, estrogen and progesterone. Estrogen stimulates the maturation of reproductive structures associated with reproduction (eg growth of the uterus and vagina) and the development of secondary female sex characteristics (pubic hair growth, enlargement of the buttocks, development of breasts, change of fat distribution in the body, and some changes in sound quality). This change in hormone balance also initiates the menstrual cycle. Menstruation cycle,


Rhythmic changes in the secretion of gonadotropic hormones in the female of many mammalian species lead to an event known as the oestrus cycle. This event means the rhythmic changes in the structure of the reproductive tract and sexual desire. The female of many species accepts the transduction with the male only within the short period of the cycle close to ovulation. This period is also the period when the inner wall of the uterus is thickest and sexual desire is the highest. In such periods the female is said to be str angry ”or in estrous. While many mammals have only one or several oestrus periods per year, some, such as rats, mice, and relatives, may be in estrus as often as every four days. If there is no fertilization, the thickened uterus wall is absorbed by the body of the tooth and normally there is no bleeding.
The reproductive cycle in humans and some other high primates differs significantly from other mammals in various aspects. There is no apparent period of anger The female is always able to accept the man during the cycle. If there is no fertilization, the surface of the thickened uterus is not completely absorbed; The menstruation cycle is 28 days on average and is repeated 13 times a year. This is a very coarse mean and there are significant differences in cycle-to-loop from person to person and even from the same person.
Now, assuming that one period is 28 days, we monitor the events occurring in each menstruation cycle, respectively. The first day of menstruation in medicine is considered the first day of the cycle. However, from a biological point of view, it is more appropriate to accept the end of the bleeding period as the beginning of the new cycle. At this point, the surface of the uterus is thin and there are no mature follicles in the ovaries. With the follicle-stimulating hormone effect of FSH secreted from the anterior pituitary, several follicles in the ovaries begin to secrete estrogen, one of the two female sex hormones, due to the synergistic effect of FSH and LH. After a short period of time, one of the follicles continues to grow and release estrogen, while the rest stop growing. Estrogen provides thickening by stimulating the surface of the uterus. This follicular phase of the cycle (growth phase), an average of 9-10 days after the end of the previous menstrual discharge. As the follicle grows, it produces even more estrogen.
As a result, the high level of estrogen reached (or, according to some researchers, the decrease in the rate of production as the estrogen reaches its peak), probablythrough GnRH secreted from the hypothalamus, stimulates sudden and large amounts of LH secretion from the pituitary. This LH explosion initiates ovulation in the follicle, which was then matured and protruded on the surface of the ovary. The mechanism of ovulation is not yet known. Some researchers believe that a slight increase in progesterone that occurs just before ovulation makes a synergetic effect with LH in initiating ovulation. Generally, it is said that the pressure of the liquid in the follicle causes the wall to explode; but on the contrary, there is evidence that this pressure actually decreases slightly just before ovulation. However, it is clear that the thinning of the follicular wall by hormone is an important factor in ovulation. Regardless of its mechanism, ovulation indicates the end of the follicular or growth phase of the cycle.
After ovulation, LH initiates some changes in follicular cells, resulting in the follicle being converted into a yellowish cell mass rich in blood vessels. This new structure formed by the effect of LH from the torn follicle is called the corpus luteum (, yellow body iyle in Latin). The corpus luteum continues to secrete estrogen from its location in the ovary, even if it is not as much as the follicle just before ovulation. The corpus luteum also secretes the second female sex hormone progesterone.
Progesterone serves to prepare the uterus for embryos. The surface of the uterus is already thickened by the effect of estrogen released in the follicular phase. Now, progesterone provides the development of a complex cloth system that extends on the surface. Although the luteal phase of the menstruation cycle is sometimes referred to as the secretory phase, this name is somewhat misleading; because at the final stages of the fertilization phase some amount of diaper activity is seen on the surface of the uterus. Without changes in the uterine surface of the progesterone, it is not possible to hold the fertilized egg in the uterus. Progesterone is a real pregnancy hormone.
In addition, a high level of progesterone prevents the onset of the next cycle, although the detailed mechanism is not fully known. Progesterone, presumably influencing the hypothalamus, suppresses GnRH secretion, thus decreasing the secretion of FSH and LH from the pituitary, thereby avoiding the LH explosion required for ovulation. Progesterone may directly affect the immature follicles in the ovary, preventing their growth and estrogen secretion. Specific in the systemAs long as an amount of progesterone is present, there is very little follicle growth. Of course, this inhibitory effect of progesterone is an important factor in regulating the duration of the menstruation cycle. This is also the basis for the effect of birth control pills. These pills contain synthetic compounds such as progesterone and estrogen. When taken on a regular basis, they inhibit the secretion of FSH and LH (presumably by suppressing GnRH secretion from the hypothalamus) and thus prevent follicle growth and ovulation sal and consequently pregnancy. Birth control pills, such as most contraceptive techniques, sometimes have undesirable side effects. These include migraine headaches, circulatory disorders, depression, decreased sexual desire, changes in skin pigmentation; and possibly an increased risk of heart attack and some types of cancer (although there is evidence that these reduce the risk for some other types of cancer). If fertilization does not occur during a normal cycle, the corpus luteum starts to regress about eleven days after ovulation and the progesterone secretion decreases. When this occurs, the thickened surface of the uterus cannot be protected further and a re-absorption of part of the surface begins. Unlike most mammals, human and some other high primates cannot absorb all of the excess tissues formed in the follicular and luteal phases of the cycle, and some of them are peeled off during the menstruation, which lasts about four to five days. If fertilization does not occur during a normal cycle, the corpus luteum starts to regress about eleven days after ovulation and the progesterone secretion decreases. When this occurs, the thickened surface of the uterus cannot be protected further and a re-absorption of part of the surface begins. Unlike most mammals, human and some other high primates cannot absorb all of the excess tissues formed in the follicular and luteal phases of the cycle, and some of them are peeled off during the menstruation, which lasts about four to five days. If fertilization does not occur during a normal cycle, the corpus luteum starts to regress about eleven days after ovulation and the progesterone secretion decreases. When this occurs, the thickened surface of the uterus cannot be protected further and a re-absorption of part of the surface begins. Unlike most mammals, human and some other high primates cannot absorb all of the excess tissues formed in the follicular and luteal phases of the cycle, and some of them are peeled off during the menstruation, which lasts about four to five days.
As a result of the regression of the corpus luteum, the level of progesterone stimulates the shielding, hypothalamus, pituitary, and FSH secretion. The blockage on the immature follicles is removed and, under the influence of FSH, they start to grow and thus a new cycle begins.
It appears that the critical event that reboots the system is probably a decrease in progesterone levels as a result of the regression of the corpus luteum. But what causes this regression? No definite answer can be given yet. This means that the basic feature in the timing of the menstrual cycle is not known. Before the sensitive methods used to measure the hormone concentrations in the blood, LH release was gradually decreased after ovulation and the level could not protect the presence of the corpus luteum when it fell sufficiently. However, it is now known that the LH level shows a sudden decrease immediately after ovulation and occurs long before the regression of the corpus luteum. Recently, some prostaglandins produced in the cows from the non-pregnant uterus and brought to the ovary with a special carrier blood vessel system, Reliable evidence has been obtained that they stop progesterone secretion. However, neither humans have such a carrier system, nor are there any concrete evidences that the human uterus sends an inhibiting agent to the ovaries. There is also the possibility that the ovary itself may stop progesterone secretion by producing prostaglandins; but there is still not enough evidence.
During the bleeding phase, especially in the first few days, the level of progesterone and estrogen released from the old corpus luteum is low and the follicles of the new cycle have not yet begun to release a significant amount of estrogen. Since the woman's body is used to function in the presence of homogen hormones after adolescence, at the end of each cycle, the decrease of these hormones luteal often leads to physiological and psychological disorders. These include hypersensitivity, depression and sometimes nausea, abdominal cramps caused by uterine contractions.
At the end of a woman's productivity period, a period of one or two years, the menopause is also seen as spiritual tension. Menopause normally occurs between 40 and 50 years of age. The main reason for this occurrence may be the decrease in the sensitivity of the ovaries to the stimulating effect of gonadotropins. The ovaries are removed, the remaining follicles disappear, and the estrogen and progesterone secretions are reduced to low levels. Consequently, there is no cyclical thickening on the surface of the uterus and thus no menstruation. Changes in hormone balance during menopause can lead to physiological and psychological disorders and new physiological difficulties remain lifelong; A common event is osteoporosis after rectification. In this, thinning and weakening of the bones is thought to be due to the absence of estrogen. In humans, we have seen that ovulation occurs roughly in the middle of the menstruation cycle. This ovulation occurs spontaneously; it is not dependent on a stimulation stimulation. However, in some mammals such as rabbits and cats, ovulation is controlled by reflex; The neural stimulation resulting from the transcription is necessary to induce secretion of the hypothalamus from the hypophysis of the LH'n-4 which ovulates. In animals where ovulation occurs with reflex, it is possible to predict exactly when ovulation occurs. The hypothalamus is required to induce secretion of LH'n-4 from the pituitary gland. In animals where ovulation occurs with reflex, it is possible to predict exactly when ovulation occurs. The hypothalamus is required to induce secretion of LH'n-4 from the pituitary gland. In animals where ovulation occurs with reflex, it is possible to predict exactly when ovulation occurs.
For example, the rabbit occurs about 101/2 hours after the transection. In human beings where ovulation, such as human, occurs spontaneously, such precise estimates cannot be made. Nevertheless, it is important to estimate the ovulation time in rhythm contraception. The rhythm method is based on the fact that fertilization can occur only in a very short period of time during each cycle. In other parts of the cycle, without the risk of pregnancy, it is possible to be copied. The available evidence shows that human egg cells begin to become devastated after 12 hours (up to 24 hours) from ovulation and are no longer fertilized. In other words, if the sperm are only present in the upper third of the oviduct between 12 and 24 hours after ovulation, fertilization may occur. In this case, the other 27 days of the 28-day cycle in theory would not be possible. Here, the life span of the female reproductive canal is important. As we said before, about 200 million sperm cells are released into the vagina at a discharge. The conditions in the vagina are quite negative for sperms and many sperm die before they have the chance to undergo a cervix. Millions die in uterus or oviduct or lose their ability to fertilize; millions of false ovidukta leaders or ovidukta never reach. Travel to the upper parts of the Ovidukt is extremely long and dangerous for such small objects. However, there is evidence to suggest that the movement of the sperm from the vagina to the upper part of the oviduct is not only dependent on the sperm's own swimming movements; female reproductive canal contractions, Increased by the prostaglandins contained in the seminal fluid and the oxytocin secreted from the posterior pituitary, it partially helps in transporting the sperm towards the target. The present findings show that human sperm can remain in the female sex canal without losing their ability to fertilize for 48 hours or less.
This period is much longer for the sperm of many other animals. For example, some bats mate in autumn; but do not ovulate until spring, after hibernation. Therefore, the sperm should remain alive for several months. In some invertebrates, such as bees and ants, sperm can be stored in the female body for years without losing their ability to fertilize. Thus, a mating can provide enough sperm for a queen bee to produce a whole reproductive life of tens of thousands or hundreds of thousands of offspring.
There is a period of up to three days that a human egg cell can survive for a maximum of one day, and sperminence is no more than two days, resulting in pregnancy. This is the day when the egg is fertilized and the following two days. But what three days? Failure to give a complete and precise answer to this question makes the rhythm method unreliable. Although it is known that these three days coincide in the middle of the menstruation cycle, it cannot be known in the middle tithe as the length of any cycle cannot be accurately predicted. In many women, the cycle is very irregular and may show deviations of 8-15 days or more. Even in women who are very regular in cycles, there may be deviations of four or five days in a year. Diseases or sadness, delaying ovulation,
There is also evidence that copulation accelerates ovulation and thus increases the chance of fertilization. Normal to short or long loops are mainly caused by a change in the duration of the follicular phase. The least variable duration of the cycle, luteal fdz, seems to be the time interval between the ovulation and the onset of the next bleeding. The average duration of this phase is 14 to 15 days. But this relatively stable duration of the luteal phase is of little help to predict the day of ovulation; because there is no way to know in advance when the next bleeding begins. Therefore, it is not possible to count back the 14th or 15th day and determine the ovulation date.
Source: poxox blogs

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