Beta actin: its implication in the seminiferous tubule

Abstract

Junctional devices in Sertoli cells play a key role in maturation and differentiation of germ cells. However, the cellular and subcellular organization of these specializations are still not totally understood. By combining light and electron microscopic techniques using â-actin immunolabeling and prosaposin and glutaredoxin antibodies to label Sertoli cytoplasm, we observed the structural (by confocal microscopy) and fine structural (by electron microscopy) organization of tight and adherent junctions, which are the morphological substrate of the blood testis barrier (BTB). The association to the beta actin also characterizes ectoplasmic specializations (ES) found at two different level of the seminiferous epithelium. We also used freeze fracture to analyze the characteristics of tubular bulbar complexes (TBC), a known component of apical ectoplasmic specializations. These different approaches also allowed us to study the complex arrangement of the actin cytoskeleton of Sertoli cells branches, which surround germ cells in different stages of the spermatogenic cycle. Our results show a consistent labelling for â-actin before, during and after the release of spermatozoa in the tubular lumen (spermiation) suggesting a significant role of the actin network in spermatic cell differentiation. In conclusion, significant interrelations among the â-actin network, the junctional complexes of the BTB and the ectoplasmic specializations were detected at different stages of the seminiferous cycle. â-actin immunolabeling and prosaposin and glutaredoxin antibodies to label Sertoli cytoplasm, we observed the structural (by confocal microscopy) and fine structural (by electron microscopy) organization of tight and adherent junctions, which are the morphological substrate of the blood testis barrier (BTB). The association to the beta actin also characterizes ectoplasmic specializations (ES) found at two different level of the seminiferous epithelium. We also used freeze fracture to analyze the characteristics of tubular bulbar complexes (TBC), a known component of apical ectoplasmic specializations. These different approaches also allowed us to study the complex arrangement of the actin cytoskeleton of Sertoli cells branches, which surround germ cells in different stages of the spermatogenic cycle. Our results show a consistent labelling for â-actin before, during and after the release of spermatozoa in the tubular lumen (spermiation) suggesting a significant role of the actin network in spermatic cell differentiation. In conclusion, significant interrelations among the â-actin network, the junctional complexes of the BTB and the ectoplasmic specializations were detected at different stages of the seminiferous cycle.