Sertoli cell tight junction dynamics: their regulation during spermatogenesis

During spermatogenesis, developing preleptotene and leptotene spermatocytes must translocate from the basal to the adluminal compartment of the seminiferous epithelium so that fully developed spermatids (spermatozoa) can be released to the tubular lumen at spermiation. It is conceivable that the opening and closing of the inter-Sertoli tight junctions (TJs) that constitute the blood-testis barrier are regulated by an array of intriguingly coordinated signaling pathways and molecules. Several molecules have been shown to regulate Sertoli cell TJ dynamics; they include, for example, transforming growth factor beta3 (TGFbeta3), occludin, protein kinase A, protein kinase C, and signaling pathways such as the TGFbeta3/p38 mitogen-activated protein kinase pathway. Yet the mechanisms that regulate these events are essentially not known. This minireview summarizes some of the recent advances in the study of TJ dynamics in the testis and reviews several models that can be used to study TJ dynamics. It also highlights specific areas for future research toward understanding the precise physiological relationship between junction dynamics and spermatogenesis.