The anterior pituitary produces and secretes two gonadotropic hormones—FSH (follicle-stimulating hormone) and LH (luteinizing hormone). Although these two hormones are named according to their actions in the female, the same hormones are secreted by the male's pituitary gland. The go-nadotropic hormones of both sexes have three primary effects on the gonads: (1) stimulation of spermatogenesis or oogenesis (formation of sperm or ova); (2) stimulation of gonadal hormone secretion; and (3) maintenance of the structure of the gonads (the gonads atrophy if the pituitary gland is removed).
The secretion of both LH and FSH from the anterior pituitary is stimulated by a hormone produced by the hypothalamus and secreted into the hypothalamo-hypophyseal portal vessels (chapter 11). This releasing hormone is sometimes called LHRH (luteinizing hormone-releasing hormone). Since attempts to find a separate FSH-releasing hormone have thus far failed, and since LHRH stimulates FSH as well as LH secretion, LHRH is often referred to as gonadotropin-releasing hormone (GnRH).
If a male or female animal is castrated (has its gonads surgically removed), the secretion of FSH and LH increases to much higher levels than in the intact animal. This demonstrates
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.