Puberty occurring either spontaneously or induced precociously in rhesus monkey (Macaca mulatta) is associated with a marked proliferation of Sertoli cells.

The pubertal ontogeny of Sertoli cell proliferation in primates is controversial. In the study of the rhesus monkey presented here, we investigated this issue during normal sexual maturation and during precocious puberty induced experimentally with pulsatile GnRH treatment. Cell number was calculated by standard stereological methods employing volume fraction of either seminiferous tubule or, whenever possible, cell nuclei. In the first experiment, testes were collected from normal monkeys at three developmental phases: neonates (7-18 days old, n = 5); juveniles (approximately 17 mo old, n = 4); and adults (5 yr and older, n = 4). In the second experiment, tissue was obtained from an additional three untreated juvenile monkeys and from six other juveniles of comparable age that had been subjected to premature activation of the pituitary-testicular axis for 5 or 10 wk with pulsatile GnRH (1 microgram/min for 3 min every 3 h). The number of Sertoli cells in adults was 6-fold greater than that in neonatal and juvenile animals. A similar increase in number of this somatic cell type was also observed during experimentally induced puberty. A less dramatic proliferation of Sertoli cells occurred during the neonatal-juvenile transition. Although the increase in Sertoli cell number between the juvenile and adult stages of development was paralleled by a comparable change in Ad and Ap spermatogonia, proliferation of these stem spermatogonia during premature activation of the pituitary-testicular axis was less striking. These results lead to the suggestion that, in primates, the onset of puberty is associated with a rapid and substantial proliferation of Sertoli cells, which is subsequently followed by amplification of stem spermatogonia. They also indicate that while Sertoli cells and stem spermatogonia proliferate during infancy and juvenile development, these earlier changes appear to be more insidious than those at puberty.