Cell association and surface features in cultures of juvenile rat seminiferous tubules

Short pieces of seminiferous tubules from juvenile rats were grown in tissue culture and studied by phase contrast light microscopy while living and by transmission and scanning electron microscopy after fixation and appropriate processing. The pieces of tubules remodeled in vitro, with the original explant becoming surrounded closely by a sheet of epithelioid cells and more peripherally by elongate cells. The epithelioid cells were identifiable as Sertoli cells because of the presence of characteristic Sertoli-Sertoli cell junctions near their upper surface. The elongate cells were derived from peritubular tissues, but could not be specifically identified as to cell type. Clusters of stellate cells and of round cells were present on the upper surface of the Sertoli cell sheets, but not on the elongate cells or the bare floor of the culture dish. The stellate cells were spermatogonia and the round cells were spermatocytes, as identified by fine structural features. Intercellular bridges were maintained between germ cells in culture without being surrounded by processes of Sertoli cells. Rudimentary junctions were present between germ cells and Sertoli cells in culture. The shape of germ cells in vitro was the same as the shape in situ, indicating that shape is an inherent feature of germ cells and is not determined by surrounding Sertoli cells.