Chapter

Physiology of Testicular Function

01/2010; DOI:10.1007/978-3-540-78355-8_2

ABSTRACT The testes produce the male gametes and the male sexual hormones (androgens). The term spermatogenesis describes and includes all the processes involved in the production of gametes, whereas steroidogenesis refers to the enzymatic reactions leading to the production of male steroid hormones. Spermatogenesis and steroido-genesis
take place in two compartments morphologically and functionally distinguishable from each other. These are the tubular compartment,
consisting of the seminiferous tubules (tubuli seminiferi) and the interstitial compartment (interstitium) between the seminiferous tubules (Figs. 2.1 and 2.2). Although anatomically separate, both compartments are closely connected
with each other. For quantitatively and qualitatively normal production of sperm the integrity of both compartments is necessary.
The function of the testis and thereby also the function of its compartments are governed by the hypothalamus and the pituitary
gland (endocrine regulation). These endocrine effects are mediated and modulated at the testicular level by local control mechanisms (paracrine and autocrine factors).

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    ABSTRACT: The two functions of the testis are androgen production and spermatogenesis. The key role in the regulation of these functions is played by the two pituitary gonadotropins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH), as supported by a vast number of experimental and clinical data. These facts have recently been corroborated by findings on patients with inactivating mutations of the gonadotropin or gonadotropin receptor genes, and by transgenic and knock-out mouse models. Besides gonadotropins, a number of other hormones contribute to testicular regulation, and there is a plethora of paracrine and autocrine regulatory effects between and within the different testicular cell compartments (see Chapter 3). However, the physiological role of these regulatory mechanisms, so far mostly demonstrated in vitro, has only recently started emerging.
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