The Endocrine Glands - The gonads
The gonads refer to both the two male testicles and the two female ovaries.
There are four hormones secreted by the gonads: the female sex hormones , estrogen and progesterone; and the male hormones, testosterone and androsterone . Each sex merely has a predominance of one or the other pair of hormones. Men have some of the female hormones, and women some of the male hormones.
In both sexes, puberty is signaled by the release of the gonadotrophic hormones (or gonadotrophins ) of the pituitary gland. These stimulate the production of sex hormones by the sex glands and the subsequent appearance of secondary sexual characteristics. In men, these include the enlargement of testicles and penis, growth of facial, axillary (armpit) and pubic hair, and enlargement of the larynx, resulting in deepening of the voice. Pubescent women also experience pubic and axillary hair growth, in addition to breast growth and changes in the genital tract that give it child-bearing capability.
Estrogen and progesterone control the cyclic changes within the uterus that involve the development, ripening, and discharge of the egg (ovulation) to be fertilized; the preparation of the lining of the uterus to receive a fertilized egg; and this lining's subsequent dismantling—all the complex biochemical events that occur as part of every woman's menstrual cycle.