Question

List the hormones involved in the development of the male and female internal and external sex organs and state their functions. (pages \(406-07\) )

Short answer

The hormones involved in the development of male and female sex organs are gonadotropins (FSH and LH), testosterone, anti-müllerian hormone (AMH), estrogens, progesterone, and Müllerian-inhibiting substance (MIS). FSH and LH are common in both males and females, stimulating the development of reproductive organs and production of other sex-specific hormones. In males, testosterone and AMH are responsible for the development of male genitalia and the regression of Müllerian ducts respectively. In females, estrogens and progesterone are essential for the development of female reproductive organs, secondary sexual characteristics, and maintenance of pregnancy, while MIS allows Müllerian ducts to develop into female reproductive structures in the absence of AMH.

Step-by-step solution

1. Hormones involved in the development of male and female sex organs

: For both males and females, there are common hormones involved in the development of sex organs, as well as hormones specific to each sex.

2. Common hormones: Gonadotropins

: Gonadotropins are hormones that regulate the development of reproductive organs in both males and females. They are produced in the anterior pituitary gland. There are two types of gonadotropins: a) Follicle-stimulating hormone (FSH): In females, FSH stimulates the development of ovarian follicles and the production of estrogens. In males, FSH stimulates the development of seminiferous tubules and sperm production. b) Luteinizing hormone (LH): In females, LH triggers ovulation and corpus luteum formation, leading to progesterone production. In males, LH stimulates Leydig cells to produce testosterone.

3. Male-specific hormones

: a) Testosterone: Produced primarily in the testes, testosterone is essential for the development of the male internal and external genitalia. Functions of testosterone include promoting the growth of testes and prostate gland, promoting sperm production, supporting the development of secondary sexual characteristics (such as facial hair, body hair, and deepening of the voice), and maintenance of sexual function. b) Anti-müllerian hormone (AMH): Produced by Sertoli cells in the testes, AMH is involved in the regression of Müllerian ducts (which would have otherwise developed into female reproductive structures) during male fetal development.

4. Female-specific hormones

: a) Estrogens: Produced mainly by the ovaries, estrogens are essential for the development of female reproductive organs, such as the uterus, fallopian tubes, and vagina. Estrogens also promote the development of secondary sexual characteristics (such as breast development and distribution of body fat), the menstrual cycle, and the maintenance of pregnancy. b) Progesterone: Produced primarily in the corpus luteum and placenta, progesterone prepares the uterus for pregnancy and maintains the uterine lining during pregnancy, preventing menstruation. It also modulates the effects of estrogens and prepares the mammary glands for lactation. c) Müllerian-inhibiting substance (MIS): In the absence of AMH, the Müllerian ducts develop into the female reproductive structures (uterus, fallopian tubes, and upper vagina).

Key concepts

Gonadotropins

Gonadotropins are like the conductors of an orchestra, skillfully guiding the development and function of reproductive organs in both males and females. These hormones, which include Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH), are released by the anterior pituitary gland, situated at the base of the brain.

In the grand concert of the female reproductive system, FSH plays a first violin role by stimulating the maturation of ovarian follicles, which are small sacs that house and release eggs. This process also leads to the production of estrogens. On the other hand, LH is like the cymbal crash that signals ovulation, encouraging the release of an egg from the ovary. Post ovulation, LH supports the corpus luteum, which secretes progesterone vital for pregnancy preparation.

For males, the melody is slightly different. FSH promotes the symphony within the seminiferous tubules, fostering sperm production. Meanwhile, LH encourages the Leydig cells in the testes to produce testosterone, the hormone that adds depth to the masculine features and fertility.

Testosterone

Testosterone steps into the spotlight during male development, asserting its influence across the body. It is produced mainly in the testes, endorsing the growth of the male internal genitalia such as the testes and prostate gland. More than just supporting 'behind the scenes', testosterone also choreographs the external presentation - by deepening the voice, enhancing the appearance of facial and body hair, and contributing to the overall male physique.

This hormone isn't only about looks; it's integral to the production of sperm, making it a key player in male fertility. Testosterone's role is not limited to the reproductive system but also extends to maintaining the libido and ensuring the maintenance of muscle strength and bone density, showcasing its vital role in holistic male health.

Estrogens

Estrogens are often associated with femininity, and rightly so. Produced predominantly in the ovaries, these hormones oversee the construction and maintenance of female reproductive structures such as the uterus, fallopian tubes, and vagina. Estrogens ensure that the stage is set for potential pregnancy.

But their influence isn't limited to reproductive organs; estrogens also contribute to the full chorus of female secondary sexual characteristics. They play a role in the growth and distribution of breast tissue, pattern of body fat deposition, and the complex cycle of skin and hair health. Additionally, estrogens take the lead in regulating the menstrual cycle and supporting pregnancy, revealing their crucial part in the intricate dance of female reproductive health.

Progesterone

Progesterone, often referred to as the hormone of pregnancy, steps up in the intricate dance of the female reproductive system once a potential pregnancy is on the horizon. After ovulation, when the LH hormone has led to the release of an egg, progesterone takes center stage. It is chiefly produced in the corpus luteum and later on by the placenta, ensuring the uterine lining is plush and ready to support a fertilized egg.

In absence of fertilization, progesterone levels decline, and menstruation begins. During pregnancy, it harmoniously works with estrogens to prevent further menstrual cycles and modulates their effects, ensuring the uterus is a welcoming environment for the developing fetus. Progesterone also prepares the mammary glands for breastfeeding, highlighting its pivotal role in the journey from conception to delivery and beyond.