The ultrastructural relationships between Sertoli cells and spermatogenic cells in the rat.

The cell-to-cell junctions between Sertoli cells and between Sertoli cells and spermatogenic cells have been described and illustrated in the rat seminiferous tubule. The most important junction is a zonula (or macula) adherens which exists between Sertoli cells on the one hand and spermatogonia on the other. No such junctions are observable between Sertoli cells and late spermatids in the Golgi, acrosomal or cap phases. Mitochondria in these spermatids are the 'energized' type and are lined up close to the inner aspect of the cell membrane; whereas in all other spermatogenic cells they are 'non-energized' and randomly orientated. Almost all the ultrastructural characteristics of steroid hormone-secreting cells have been observed in Sertoli cells. The functional significance of these findings is discussed.