Functional anatomy of the hypothalamic–Pituitary–gonadal axis and themale reproductive tract

Anatomy of reproductive function he reproductive functional axis of the male can be divided into three major subdivisions: (1) the hypothalamus, (2) the pituitary gland, and (3) the testis. Each level elaborates a signal, or transmitter molecule, that stimulates or inhibits the subsequent level of the axis.he end result is the production and expulsion of semen that contains spermatozoa.his chapter examines the hypothalamic–pituitary–gonadal (HPG) axis, and reviews the functional anatomy of the testis, epididymis, vas deferens, seminal vesicles, prostate, and penis. Hypothalamus and anterior pituitary gland he control of male sexual and reproductive function begins with secretion of gonadotropin-releasing hormone (GnRH) by the hypothalamus (Fig. 1.1). his hormone in turn stimulates the anterior pituitary gland to secrete two downstream hormones (termed gonadotropins). hese hormones are luteinizing hormone (LH) and follicle-stimulating hormone (FSH). LH is the primary stimulus for the testicular secretion of testosterone, while FSH mainly stimulates spermatogenesis. Gonadotropin-releasing hormone (GnRH) he neuronal cells of the arcuate nuclei of the hypothalamus secrete GnRH, a 10-amino-acid peptide. he endings of these neurons terminate in the median eminence of the hypothalamus, where they release GnRH into the hypothalamic–hypophysial portal vascular system. he GnRH is transported to the anterior pituitary gland via the hypophysial portal blood and stimulates the release of the two gonadotropins, LH and FSH [1]. he output of GnRH is inluenced by three types of rhythmicity: seasonal, on a timescale of