Hormones in Reproduction

Hormones and Reproduction

Hormones are chemical messengers secreted by endocrine glands in the body.
They play a crucial role in the reproductive system, controlling the menstrual cycle in women, spermatogenesis in men, and several aspects of pregnancy and foetal development.

In males, the hormone testosterone is secreted by the testes. This hormone regulates spermatogenesis, the process of sperm production.
Other roles of testosterone include the development of male secondary sexual characteristics like the deepening of the voice, facial and body hair growth, and muscle development.

The two main hormones involved in female reproduction are oestrogen and progesterone, produced by the ovaries.
Oestrogen governs the feminine body development during puberty, stimulates the lining of the womb to thicken after menstruation and initiates the release of an egg at ovulation.
Progesterone is involved in maintaining the lining of the womb during the second half of the menstrual cycle and during pregnancy. It inhibits the release of further eggs until a pregnancy ends or enters the next menstrual cycle.

The menstrual cycle is regulated by a complex interaction of hormones which include Follicle Stimulating Hormone (FSH), Luteinising Hormone (LH), oestrogen and progesterone.
FSH stimulates the growth of a follicle in the ovary.
LH triggers the release of an egg from the ovary (ovulation).
Both FSH and LH are secreted by the pituitary gland in the brain.

If the egg is fertilised, Human Chorionic Gonadotropin (HCG) is secreted by the placenta. This hormone maintains the production of progesterone and prevents menstruation, allowing the pregnancy to continue.
HCG is also the hormone detected in pregnancy tests.
During labour, the hormone oxytocin is secreted which initiates and maintains contractions of the uterus.

Artificial versions of FSH and LH are used in In Vitro Fertilisation (IVF) to stimulate the maturation and release of multiple eggs.
Once the eggs are harvested and fertilised in a lab, one or two are inserted into the woman’s uterus in the hope of achieving pregnancy.
IVF often involves the use of additional hormones such as progesterone to prepare and maintain the uterus lining for potential implantation of the fertilised egg.