Types and Functions of Reproductive Hormones

Although an organism's sex is determined at fertilization, the reproductive organs do not develop until after two months of gestation. The maturation of the genitals occurs during the age known as puberty.

Puberty is when the gonads (sex glands) begin to produce mature sex cells, or gametes, known as spermatozoa in males and ova in females. Males experience puberty between the ages of 14 and 16, while females experience it earlier, between the ages of 11 and 14.

Puberty is characterized by the onset of secondary sexual characteristics. In males, secondary sexual characteristics include a change in voice, the development of a chest area, the development of a mustache, beard, sideburns, or genital hair. In females, secondary sexual characteristics include a high-pitched or soft voice, breast development, enlargement of the hips, and the growth of genital hair.

In men, signs of puberty are seen with the release of sperm for the first time, while in women, the symptoms of puberty are marked by the occurrence of menstruation or the first period.

These signs of puberty are actually influenced by certain sex hormones. The sex hormones that play a role in the growth of the genital organs are FSH (Follicle Stimulating Hormone), LH (Luteinizing Hormone), testosterone, estrogen, progesterone, oxytocin, relaxin, and lactogen (prolactin). Each of these hormones has different effects, which will be explained in more detail below.

1. FSH (Follicle Stimulating Hormone)

This hormone is produced by the pituitary gland. FSH plays a role in the formation and maturation of spermatozoa (sperm), known as spermatogenesis, and ova (oogenesis). FSH also stimulates the production of testosterone in men and estrogen in women.

2. LH (Luteinizing Hormone)

This hormone is also produced by the pituitary gland. It stimulates the formation of the corpus luteum in the ovary after ovulation (the release of an egg).

3. Testoseron

This is a hormone produced by the testes and plays a role in spermatogenesis and the appearance of secondary sexual characteristics in males.

4. Estrogen

This hormone is produced by the Graafian follicles in the ovaries. It plays a role in oogenesis and the development of secondary sex characteristics in females. It also stimulates LH production and inhibits FSH production.

5. Progesterone

This hormone is produced by the corpus luteum in the ovary. It plays a role in the formation of the endometrium lining the uterine wall to receive a fertilized egg. During pregnancy, progesterone, together with estrogen, maintains the growth of the endometrium, forms the placenta, prevents uterine muscle contractions, and stimulates the mammary glands to produce breast milk.

6. Oxytocin

This hormone is produced by the pituitary gland. Its role, during the birth process, is to stimulate the initial contractions of the uterine muscles.

7. Relax

This hormone is produced by the placenta, and plays a role in stimulating relaxation of the pelvic ligaments during the birth process.

8. Lactogen

Produced by the pituitary gland which works together with progesterone to stimulate the formation of breast milk.