Pulsatile stimulation with recombinant single chain human luteinizing hormone elicits precocious Sertoli cell proliferation in the juvenile male rhesus monkey (Macaca mulatta)

In this study, we determined the relative role of LH and FSH in initiating the pubertal proliferation of Sertoli cells in primates, Sixteen juvenile m ale rhesus monkeys (Macaca mulatta) bearing venous catheters received inter mittent intravenous infusions of single chain human LH (schLH) or recombina nt human FSH (rhFSH) or a combination of both for 11 days, The schLH infusi on elicited a physiological testosterone response. On Day 11, monkeys were castrated, and one-half of a testis was fixed in Bouin's fluid. Infusion of the gonadotropins, either alone or in combination, effected a significant increase in testicular weight, seminiferous cord diameter, and the number o f Sertoli cells per testis (schLH, 295 +/- 46 x 10(6); rhFSH, 342 +/- 64 x 10(6); LH + FSH, 298 +/- 26 x 10(6) versus vehicle, 204 +/- 26 x 10(6)). Th e latter finding indicated that LH, in addition to FSH, plays a critical ro le in the initiation of the pubertal proliferation of Sertoli cells in prim ates. Moreover, combined gonadotropin treatment led to the appearance of ge rm cells as mature as early primary spermatocytes, indicating that initiati on of spermatogenesis had been set in motion. Because the duration of hormo ne stimulation was only 11 days, the latter result suggests that Leydig and Sertoli cells of the juvenile monkey testis can immediately transduce a go nadotropin signal to the germ cell.