PROLIFERATION OF NEWT SPERMATOGONIA BY MAMMALIAN FSH VIA SERTOLI CELLS IN-VITRO

Our previous studies showed that mammalian follicle-stimulating hormon e (FSH) stimulated the proliferation and differentiation of secondary spermatogonia into primary spermatocytes in organ culture of testes fr agments from Cynops pyrrhogaster. To elucidate how FSH stimulates sper matogonial proliferation, we studied the interaction of spermatogonia with somatic cells in the presence or absence of FSH in cultures of ag gregated cells derived from fractionated cell populations. When sperma togonia or those with somatic cells were cultured, they formed aggrega tes with themselves or with somatic cells, respectively. Most of the s omatic cells in the aggregates were Sertoli cells, judged by the lipid droplets in their cytoplasm. [H-3]thymidine incorporation into aggreg ates and autoradiography demonstrated spermatogonial proliferation tha t was enhanced in the presence of FSH and somatic cells (most probably Sertoli cells), but not in the absence of FSH or in the presence of l uteinizing hormone (LH). To examine whether direct contact between spe rmatogonia and Sertoli cells is indispensable for the stimulation of s permatogonial proliferation by Sertoli cells, the two cell types were separated by a 0.4 mu m pore filter in two compartments of a bicameral chamber. In this case, Sertoli cells did not stimulate spermatogonial proliferation in the presence of FSH, indicating that direct contact between spermatogonia and Sertoli cells is indispensable for the stimu lation of spermatognial proliferation by Sertoli cells. Finally, Serto li cells isolated from the testes from the primary spermatocyte stage did not stimulate spernatogonial proliferation in the presence of FSH. This result indicated that the function of Sertoli cells with respect to their stimulation of proliferation was stage-specific. (C) 1995 Wi ley-Liss, Inc.