Sertoli-Sertoli and Sertoli-germ cell interactions and their significance in germ cell movement in the seminiferous epithelium during spermatogenesis
Mruk,Dolores D.; Cheng,Chuen-yan
Endocrine Reviews 25(5): 747-806
Publication date: 2004
Spermatogenesis is the process by which a single spermatogoniumdevelops into 256 spermatozoa, one of which will fertilize theovum. Since the 1950s when the stages of the epithelial cyclewere first described, reproductive biologists have been in pursuitof one question: How can a spermatogonium traverse the epithelium,while at the same time differentiating into elongate spermatidsthat remain attached to the Sertoli cell throughout their development?Although it was generally agreed upon that junction restructuringwas involved, at that time the types of junctions present inthe testis were not even discerned. Today, it is known thattight, anchoring, and gap junctions are found in the testis.The testis also has two unique anchoring junction types, theectoplasmic specialization and tubulobulbar complex. However,attention has recently shifted on identifying the regulatorymolecules that "open" and "close" junctions, because this informationwill be useful in elucidating the mechanism of germ cell movement.For instance, cytokines have been shown to induce Sertoli celltight junction disassembly by shutting down the production oftight junction proteins. Other factors such as proteases, proteaseinhibitors, GTPases, kinases, and phosphatases also come intoplay. In this review, we focus on this cellular phenomenon,recapping recent developments in the field.