Endocrine glands are ductless glands; they secrete chemicals directly into the blood. It is therefore proposed that gynecomastia probably results from failure of adequate testosterone action on the breast primordia during embryonic differentiation. The reproductive system is controlled by chemicals called hormones.
Though it marks a definitive and probably mature stage of uterine development, it does not usually signify the attainment of full reproductive function. All rights reserved. Views Read Edit View history.
Females have 2 ovaries, each about the size of a walnut, located on either side of the lower abdominal cavity. The Testes and Scrotum. At one extreme one may find a perfectly healthy girl who has not yet menstruated though her breasts and pubic hair are characteristic of the adult and she is already two years past her peak height velocity; and at the other, a girl who has passed all the stages of puberty within the space of two years.
Secondary sex characteristics include, for example, the manes of male lions the bright facial and rump coloration of male mandrillsand horns in many goats and antelopes. The hormone then produces a response in its target tissue the ovaries in females by controlling development of the follicles containing immature eggs; in males, the target tissue is the testes and FSH controls the development of sperm.
Despite the undoubted importance of the primary characteristics, it would be a failure without secondary sexual characteristics. Chapter Load Next Page. The hypothalamus and pituitary gland, which are in the brain, initiate puberty. During puberty, sexual development occurs in a set sequence.
In females, breasts are a manifestation of higher levels of estrogen ; estrogen also widens the pelvis and increases the amount of body fat in hips, thighs, buttocks, and breasts. Testosterone is responsible for the development of secondary sex characteristics, features that stimulate male development including characteristics that are not part of the reproductive system, such as facial hair growth and voice change.
The concept of developmental age, as opposed to chronological age, is an important one. Check for Understanding What is the function of the reproductive system? Male Reproductive System.