Cellular Interactions in the Seminiferous Epithelium

Abstract Cell-cell interactions are essential to the development, maturation, and mature function of the seminiferous tubule, the site of spermatogenesis. These interactions occur between Sertoli cells and the underlying peritubular myoid cells, between adjacent Sertoli cells, between Sertoli cells and their surrounding spermatogenic cells, and are manifest in the morphology of the seminiferous epithelium. For example, interactions between Sertoli cells and the underlying peritubular myoid cells are evident in their coordinate deposition of the basement membrane of the seminiferous epithelium (Skinner et al., 1985). Interactions between adjacent Sertoli cells are obvious in their formation of both tight and gap junctions (Gilula et al., 1976). Finally, interactions between Sertoli cells and germ cells are obvious in the desmosomes, ectoplasmic specializations, and the tubulobulbar complexes formed between these cells (Russell et al., 1983). These extensive cellcell interactions are also manifest in the highly ordered spatial arrangement of germ cells within the seminiferous tubule. Particular types of germ cells reside next to specific areas of Sertoli cell plasma membrane: spermatogonia and early preleptotene spermatocytes are found between the basement membrane of the seminiferous tubule and the basal plasma membrane of Sertoli cells. Spermatocytes, once they cross the blood-testis barrier, reside next to them basolateral surfaces of Sertoli cells just above the blood-testis barrier, whereas spermatids are adjacent to the more apical plasma membrane domains of the Sertoli cell (Weber et al., 1983). This segregation of the particular types of germ cells along different domains of the Sertoli cell plasma membrane has led to the hypothesis that specific and different interactions between Sertoli cells and germ cells occur along the different domains of the Sertoli cell (Wright, 1988).