CONICET | Buscador de Institutos y Recursos Humanos

ABSTRACT ? Junctional devices in Sertoli cells play a key role in maturation and differentiation of germ cells [1]. However, the cellular and subcellular organization of these specializations is still not totally understood. By combining light and electron microscopic techniques using â-actin [2] 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) [3]. The association to â-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 tubulobulbar complexes [4], a known component of apical ectoplasmic specializations. Also, â-actin was quantified (Western blot technique) in relation to the spermiation period in different segments of the seminiferous tubules visualized by transillumination under stereomicroscopy. These different approaches allowed us to study the complex arrangement of the actin cytoskeleton of Sertoli cell branches, which surround germ cells in different stages of the spermatogenic cycle. Our results show a significant increase and labelling of â-actin during the release of spermatozoa in the tubular lumen (spermiation) suggesting a significant role of the actin network in spermatic cell differentiation and release. In conclusion, consistent 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. This work is currently in press [5]. Supported by grants from Cuyo National University, Mendoza, Argentina.