The role of follicle stimulating hormone in testicular function of the mature rhesus monkey

Abstract

In the rat, whilst FSH has been shown to be necessary for the initiation of spermatogenesis, this hormone does not appear to be involved in the maintenance of spermatogenesis in the mature animals. Since the role of FSH has not been conclusively established in primate species, including humans, a study based on the neutralization of FSH by passive immunization with specific FSH antibodies was initiated in adult male rhesus monkeys.Prior to the actual study an antiserum pool was generated from 4 monkeys actively immunized with highly purified ovine FSH. In this FSH antiserum there was no evidence for the existence of LH antibodies, and the capacity of the antiserum to neutralize rhesus FSH was demonstrated by bioassay. Because of marked circannual variations in testicular functions passive immunization with FSH-antiserum was performed during the period of full testicular development in 4 other monkeys. FSH antiserum was injected for 106 days (i.e. a period covering the full duration of the total spermatogenetic process twice). Four further monkeys serving as controls were injected with normal rhesus serum for the same period. Testicular volume and histology, anti-FSH-titer, seminal parameters, serum testosterone, and LH were monitored at regular intervals. In the passively immunized animals the testicular volume decreased by 50%, sperm counts decreased below control counts, histology revealed reduction of the tubular diameter by 40%, derangement of spermatogenesis and, on instances, tubuli with Sertoli cells only. Leydig cells appeared histologically normal, although testosterone levels in the passively immunized monkeys tended to be lower than in control animals. Values were not significantly different at the end of the observation period.From these results it can be concluded that in contrast to the rat FSH plays a specific role in the maintenance of spermatogenesis in the mature rhesus monkey.

Localization of Luteinizing Hormone, Follicle-Stimulating Hormone, Prolactin, and Their Receptors in Human and Rat Testis Using Immunohistochemistry and Radioreceptor Assay*

“…Whereas the main target of FSH action is the tubules, administration of FSH antiserum decreased the plasma testosterone levels in rhesus monkeys, suggesting an influence of FSH on the Leydig cell function (35). Perhaps the FSH positive cells found in interstitial tissue mediate FSH action on Leydig cells by a local intercellular regulatory mechanism.…”

Qualitative and Quantitative Decline in Spermatogenesis of the Follicle-Stimulating Hormone Receptor Knockout (FORKO) Mouse1

“…The critical need for FSH in maintaining qualitative and quan- titative spermatogenesis has been a topic of debate [2] with different interpretations depending upon the species. A large body of evidence available hitherto suggests that FSH is required for primate spermatogenesis [3][4][5][6][7][8][9][10][11][12]. However, there are differing views about the role played by FSH in regulating spermatogenesis in rodents, particularly in the adult [13][14][15][16][17][18].…”

Reinitiation of sperm production in gonadotropin-suppressed normal men by administration of follicle-stimulating hormone

“…For example, administration of highly specific, neutralizing antibodies to FSH has no effect on testicular function in adult male rats (6). In contrast, either passive administration or active induction of neutralizing antibodies to FSH in adult male monkeys has been reported to decrease sperm production and fertility (7)(8)(9)(10)(11). High-dosage T administration has been demonstrated to restore and maintain spermatogenesis in hypophysectomized male monkeys and rats (1,(12)(13)(14).…”