Structure and possible functional role of septate junctions in the ovotestis of a pond snail: inter-Sertoli junctions.

Junctions between Sertoli cells, which form a continuous layer at the periphery of the 'acinus' in the ovotestis of Biomphalaria glabrata (mollusc gastropod), have been studied with conventional sections, lanthanum impregnation, replicas and scanning analysis of unstained sections. Extensive undulating septate junctions link Sertoli cells, which surround the various stages of spermatid differentiation. The morphology of the pleated septate junctions here presented indicates a possible role as a permeability barrier, which might result from the peculiar organization of the septa. The junctional complex is formed of areas where septa are parallel and regularly spaced, alternating with areas where septa separate and assemble with others, thus creating a complex system of channels, completely compatible with the sealing properties expected for these junctions. The morphology of septa, their possible anchorage within the membranes, and the interconnections linking the closely parallel septa are presented.