SERTOLI-CELL DIFFERENTIATION IN THE TESTES OF MICE GENETICALLY DEFICIENT IN GERM-CELLS

Mutations rendering mice deficient in germ cells provide a natural experimental system for investigation of the differentiation of Sertoli cells without the normal number of germ cells. In the present study, use was made of 2 viable mutants (atrichosis, at/at, and dominant spotting, W/W(v)) with testes grossly deficient in germ cells bacause of the failure of the genital ridges to become adequately populated with germ cells. Ultrastructural examination of prepuberal testes of such mice revealed that essentially normal, both structural and temporal, maturation of the Sertoli cells occurred. In particular, there was normal differentiation of the typical tripartite nucleolus, the Sertoli cell junctions and mitochondria. We conclude that the normal complement of differentiating germ cells is not a prerequisite for structural differentiation of Sertoli cells.