Junctional complexes between the Sertoli cells in the testis of the crayfish,Procambarus paeninsulanus.

The testis of the crayfish,Procambarus paeninsulanus, was prepared for light and electron microscopic study. It is composed of tubules containing germ-spermatogenic and somatic-Sertoli cells. In sections of tubules lacking sperm, the Sertoli cells rest on the basement membrane. A desmosome-like junction is found near the luminal surface between two adjacent Sertoli cells. It is closely associated with a long, septate junction. Between Sertoli cells which have surrounded numerous spermatids, the undulating membranes exhibit profiles of pleated septate junctions in tangential sections. The morphology of the pleated septate junctions between adjacent Sertoli cells suggests a possible role as a permeability barrier.