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Hormones

The Male Reproductive Organs

Male reproductive hormones come from the hypothalamus, the anterior pituitary, and the testes. As in females, GRH is released from the hypothalamus which stimulates LH and FSH release from the pituitary. In males, LH and FSH facilitate spermatogenesis. The steroid hormone testosterone is secreted from the testes and can be detected in early embryonic development up until shortly after birth. Testosterone levels are quite low until puberty. At puberty, rising levels of testosterone stimulate male reproductive development including secondary characteristics.

LH stimulates testosterone release from the testes. FSH promotes early spermatogenesis, whereas testosterone is required to complete spermatogenic maturation to facilitate fertilization. In addition to testosterone, LH, and FSH, the male also secretes prostaglandins. These substances promote uterine contractions which help propel sperm towards an egg in the fallopian tubes during sexual intercourse. Prostaglandins are produced in the seminal vesicles, and are not classified as hormones by all authorities.

See also Biological rhythms; Cell; Endocrine system; Exocrine glands; Glands; Growth hormones; Reproductive system.


Resources

Books

Burnstein, K. L. Steroid Hormones and Cell Cycle Regulation. Boston: Kluwer Academic Publishers, 2002.

Engelking, L. R. Metabolic and Endocrine Physiology. Jackson, WY:, Teton NewMedia, 2000.

Goffin, V., P. A. Kelly. Hormone Signaling. Boston: Kluwer Academic Publishers, 2002.

Griffin, J. E., and S. R. Ojeda Textbook of Endocrine Physiology. New York: Oxford University Press, 2000.

Kacsoh, B. Endocrine Physiology. New York: McGraw-Hill Health Professions Division, 2000.


Louise Dickerson

KEY TERMS

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Amino acid

—An organic compound whose molecules contain both an amino group (-NH2) and a carboxyl group (-COOH). One of the building blocks of a protein.

Androgen

—Any hormone with testosterone-like activity (i.e. it increases male characteristics).

Homeostasis

—A condition of chemical and physical equilibrium in the human body.

Plasma

—The non-cellular, fluid portion of blood in which the concentration of most molecules is measured.

Additional topics

Science EncyclopediaScience & Philosophy: Heterodyne to Hydrazoic acidHormones - Mechanisms Of Action, The Hypothalamus, The Pituitary Gland, The Thyroid Gland, The Parathyroid Glands - Major hormones