Chapter

Physiology of Testicular Function

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: Two concepts have been put forward to explain the regulation of testicular function. Firstly, it has been suggested that testicular function is regulated primarily by pituitary gonadotropins (endocrine regulation). Secondly, it has been proposed that the “testis is not a mass of independently developing cells” (Roosen-Runge, 1952), so there are presumably local regulatory mechanisms to coordinate the activities of testicular cells (paracrine regulation). It is now generally accepted that there is no conflict between the concepts of peripheral control of testicular function and intratesticular control. The integration of these two concepts accounts for gonadotrophins regulating testicular paracrine activities and some paracrine factors regulating the testicular effects of pituitary hormone and exerting endocrine control over pituitary function.
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    ABSTRACT: To examine the role of recombinant human follicle stimulating hormone (rhFSH) in male idiopathic infertility a randomized, double-blind, placebo-controlled study was performed. Of 211 patients screened, 67 were finally included. After two pre-examinations, patients were randomized and treated for 12 weeks, either with 150 IU rhFSH or with placebo. Examinations (physical examination, scrotal ultrasonography, semen analysis, hormone measurements, and in 31 patients electron microscopy (EM) of spermatozoa were performed 6 and 12 weeks after treatment initiation and 6 and 12 weeks after completion of treatment. Pregnancies were recorded for a further 3 months after the last examination. Of the 67 patients included in the study, 34 treated and 31 placebo patients could be analysed. In the treated group, FSH was elevated compared to baseline values (P < 0.001). At the end of treatment testicular volume in the treated group was increased compared to placebo (P < 0.05) and baseline (P < 0.001). Apart from an increase in sperm motility (P < 0.05) in the placebo group and in sperm DNA condensation (P < 0.001) in the treated group no significant changes were observed in semen parameters. Two spontaneous pregnancies in partners of men in the treated group and none in the placebo group occurred. However, two pregnancies occurred in partners of men in the placebo group induced by intrauterine insemination or intracytoplasmic sperm injection. In conclusion, at the chosen dose and duration, rhFSH did not lead to an improvement of conventional or EM sperm parameters nor to an increase in pregnancy rates. However, the increased testicular volume and sperm DNA condensation give reason for further investigations.
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