Overview of the Endocrine System
The gonads produce and secrete three major categories of steroid hormones: androgens, estrogens, and progestins. (The synthesis of estrogens and androgens is controlled by FSH and LH from the anterior pituitary gland.) All three hormones are found in both male and females, but in different proportions. Produced in the testes in males and ovaries in females, these steroids affect growth and development, and also regulate reproductive cycles and sexual behavior.
The testes synthesize androgens, such as testosterone. In general, androgens stimulate the development and maintenance of the male reproductive system and are responsible for male secondary sex characteristics. Estrogens, the most important of which is estradiol, maintain the female reproductive system and promote development of female secondary sex characteristics. Progestins, which include progesterone, are involved primarily in preparing and maintaining the uterus to support the growth and development of an embryo.
Keywords: gland | gonad | hormone | human | ovary | reproduction | steroid | testes | endocrine system
- Campbell, N.A., and Reece, J.B. (2002). Biology, 6th Edition. San Francisco, CA: Pearson Benjamin Cummings.
- Clark, Joe O.E. (1999). A Visual Guide to the Human Body. London: Barnes and Noble, Inc.
- SEER Training Modules: Gonads. Illustrations courtesy of the National Cancer Institute, NIH.
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