Anatomy of Sexual development

Credit: from Pexels

INTRODUCTION
Soon after the egg is fertilized, the sexual systems start to develop, and around a month following conception, the primordial gonads start to form. Even though a child's sexual system is still developing while they are in the womb, there aren't many changes before puberty

The development of a person's sexual organs while they are still embryos or fetuses.

If there was no chemical stimulation, the clitoris and vagina of every fertilized egg would grow on their own. If a single gene on the Y chromosome caused the same chain of events to happen to a person, the outcome of this situation would be different. The acronym for this construction is the SRY (Sex-determining Region of the Y Chromosome). Those who are missing a Y chromosome are also missing the gene that codes for SRY. Even if an individual does not have a functioning copy of the SRY gene, they will normally produce ovaries and a uterus.

The term "bipotential tissue" refers to a type of tissue that has the capability of developing into either testes or ovaries, and this group of cells is present in all embryos. Other genes that might lead to the formation of ovaries are prevented from doing so by the SRY gene, which actively recruits other genes that begin the process of developing the testes. Germ cells in the bipotential gonads go through a process of differentiation into spermatogonia when stimulated by SRY, which is part of the cascade. Without SRY, other genes would be turned on, oogonia would form, and in the primitive ovary, primordial follicles would grow.

Interstitial cells, which are also called Leydig cells, make testosterone soon after the testis is done growing. Testosterone has the ability to exert an effect on tissues that are bipotential. When cells are exposed to testosterone, for example, they develop into the glans penis rather than the glans clitoris. These cells have the potential to become either the glans penis or the glans clitoris. In the absence of testosterone, these cells will instead develop into the clitoris.

There are some parts of the reproductive system that do not have bipotential tissues. One of two early duct systems gives rise to the uterus, the uterine tubes, and part of the vagina, as well as the epididymis, the ductus deferens, and the seminal vesicles. These structures include the uterus, uterine tubes, and part of the vagina; and the epididymis.

In order for the internal sexual organs to grow properly, one set of ducts has to mature while the other set of ducts needs to deteriorate. Since sustentacular (Sertoli) cells make a hormone that causes the paramesonephric (Müllerian) duct to break down, it is very unlikely that a uterus would form. At the same time, testosterone makes the mesonephric (Wolffian) duct grow, which leads to the development of the epididymis and vas deferens. Without this sustentacular cell hormone release, the paramesonephric duct will now grow; and without testosterone, the mesonephric duct will degenerate. Because of this, it is likely that when the baby is exposed to certain environmental factors, it will form a uterus instead of an epididymis or a vas deferens. Look for more articles on the development of the fetus if you want more information and a diagram showing how the testes and gonads differentiate.

There are many possible reasons why a person's sexual organs might develop differently than what has been described in the past. Because of this, it is important to place intersex anatomy somewhere on the range of normal human differences that exist between the two binary genders of female and male. In rare cases, the receptors that the hormones normally attach to may not form. This can be a problematic situation. For example, a person with XY chromosomes and an SRY gene will still release hormones from the sustentacular cells even if they have a condition called "androgen insensitivity." These hormones cause the paramesonephric duct to degrade, which means that a uterus cannot form in the body. They will also make testicles, which will make testosterone and other androgens. However, the cells won't be able to respond to the hormones because they don't have the receptors that are needed to bind to the hormones. As a result, the epididymis and vas deferens are not created, and instead, the external genitalia grow into a clitoris and a vagina. An individual who has XY chromosomes, a clitoris, a vagina, and testes that have not descended but lack a uterus is the end product of this process.

In contrast to what was said before, hormone release that goes beyond what the chromosomes expect can cause a condition called intersex. Congenital adrenal hyperplasia, which is characterized by an increase in the amount of androgens produced by the adrenal glands, is more common in people with XX chromosomes. When a baby is born, the clitoris may look like a penis because the end result is a clitoris that is much bigger than usual. The following graph shows a range of clitoral diameters that could happen in people with adrenal hyperplasia. These XX people may also make more androgen because their body hair is thicker, their voices are deeper, and their bodies are more muscular.

When an XY person's normal amount of androgen production drops, this could lead to a micropenis, which is a penis that is much smaller than the average size. This supports the idea that the size range of a person's external genitalia, from the clitoris to the penis, is based on how much androgen they are exposed to over the course of their life. Surgical intervention is not essential for this spectrum of typical human variation; all that is needed is an open mind to the possibilities that natural variation can bring about. People with intersex anatomy don't have a higher risk of health problems if they are left to develop on their own. But early surgery can cause problems like nerve damage and infections.

Beginning of puberty

The period of development known as puberty is when people reach sexual maturity. The maturation of the reproductive systems and the emergence of secondary sex characteristics, which are physical changes in the body, are caused by a coordinated release of hormones from the gonads (either testosterone or estrogen), the anterior pituitary (LH and FSH), the hypothalamus (GnRH), and the hypothalamus (GnRH).

By the age of eight or nine, when LH production can be detected, the first changes start to occur. The production of LH happens predominantly at night while you sleep and occurs years before the physical changes associated with puberty. The hypothalamus and pituitary's negative feedback mechanism has a very high sensitivity in prepubescent children. This implies that extremely low levels of androgens or estrogens will have a negative feedback loop on the brain and pituitary, preventing high levels of GnRH, LH, or FSH from being produced.

Two changes in sensitivity happen as puberty gets closer. The first is a reduction in the hypothalamus' and pituitary's sensitivity to negative feedback, which results in an increase in the amount of sex steroid hormones needed to cease LH and FSH production. The second change in sensitivity is a rise in the gonads' receptivity to the FSH and LH signals, which means that adult gonads respond to gonadotropins more readily than do those of children. These two adjustments allow the levels of LH and FSH to gradually rise, which in turn causes the gonads to develop and mature and trigger the onset of spermatogenesis and folliculogenesis as well as the release of increasing amounts of sex hormones.

The age at which puberty first appears can vary depending on a number of variables, including age, genetics, environment, and psychological stress. Several studies suggest a connection between the start of puberty and the body's fat reserves. Both sexes have been shown to be affected by this phenomenon. Menarche appears to be strongly influenced by body fat, which correlates with adipose cells' release of the hormone leptin. This may partially reflect the high metabolic expenditures of nursing and pregnancy. Gymnasts and other lean, physically demanding people frequently have a delayed start of puberty.

Signs of adolescence

Differences in the amounts of steroid hormones also influence the development and function of secondary sexual characteristics.

During puberty, a girl's body makes more estrogen than normal, which usually causes breast tissue to grow. After this, hair starts to grow in the armpit and in the area around the pubic bone. Often beginning somewhere between the ages of 9 and 11, a growth spurt can continue anywhere from one to three years. During this time, a person's height could grow by an average of 3 inches per year. The onset of menstruation, or menarche, is the next stage in the puberty process that is caused by estrogen.

The production of testosterone goes up, which causes the testicles to get bigger. This is often the first sign that puberty has started that can be seen. This is then followed by the growth and pigmentation of the scrotum as well as the growth of the penis. The next change is that hair starts to grow, starting with hair on the chest, armpits, and pubic area. Because testosterone speeds up the growth of the larynx and makes the vocal folds thicker and longer, the voice becomes deeper and lower in pitch.

Although the age at which a person has their first viable ejaculation is normally about 15 years old, the exact age can vary greatly from one person to the next. Throughout puberty, the size of the prostate typically increases by a factor of two. Height can increase by as much as 4 inches each year during a growth spurt that happens at the conclusion of puberty, which typically occurs between the ages of 11 and 13. Pubertal development in some people can last well into their early twenties.

Referrences

• C. (n.d.). Male Reproductive System: Structure & Function. Cleveland Clinic. https://my.clevelandclinic.org/health/articles/9117-male-reproductive-system

• Human sexual activity - Development and change in the reproductive system. (n.d.). Encyclopedia Britannica. https://www.britannica.com/topic/human-sexual-activity

• Biga, L. M., Dawson, S., Harwell, A., Hopkins, R., Kaufmann, J., LeMaster, M., Matern, P., Morrison-Graham, K., Quick, D., & Runyeon, J. (n.d.). 27.2 Development of Sexual Anatomy – Anatomy & Physiology. 27.2 Development Of Sexual Anatomy – Anatomy & Physiology. https://open.oregonstate.education/aandp/chapter/27-2-development-of-sexual-anatomy/

• Development of the Male and Female Reproductive Systems | Anatomy and Physiology II. (n.d.). Development of the Male and Female Reproductive Systems | Anatomy and Physiology II. https://courses.lumenlearning.com/suny-ap2/chapter/development-of-the-male-and-female-reproductive-systems/

• Male Reproductive System (for Teens) - Nemours KidsHealth. (2019, July 1). Male Reproductive System (for Teens) - Nemours KidsHealth. https://kidshealth.org/en/teens/male-repro.html#:~:text=During%20the%20first%20stage%20of,time%2C%20the%20voice%20also%20deepens.

• Rao, P. K., & Burnett, A. L. (2012, January 1). Development of the Male Reproductive System. Development of the Male Reproductive System | SpringerLink. https://doi.org/10.1007/978-1-4471-4405-2_2

• A, A. P., Arbor, T. C., & Krishan, K. (2022, September 8). Embryology, Sexual Development - StatPearls - NCBI Bookshelf. Embryology, Sexual Development - StatPearls - NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK557601/