The actin filament network associated to Sertoli cell ectoplasmic specializations

Junctional devices in Sertoli cells conform the blood-testis barrier and play a key role in maturation and differentiation of germ cells. The spacial distribution of ectoplasmic specializations of Sertoli cells was studied by beta-actin immunolabelling, using laser confocal and transmission electron microscopy. For confocal microscopy, beta-actin immunolabelling of ectoplasmic specializations was studied over the background of either prosaposin or glutaredoxin immunolabelling of the Sertoli cytoplasm. Labelling was found near the basal lamina, surrounding early spermatocytes (presumably in leptotene-zygotene) or at one of two levels in the seminiferous epithelium: (1) around deep infoldings of the Sertoli cell cytoplasm, in tubular stages before spermiation, and (2) in the superficial part of the seminiferous epithelium, in tubular stages after or during spermiation. For transmission electron microscopy, beta-actin immunolabelling of ectoplasmic specializations was also used. Ectoplasmic specializations were found at two different levels of the seminiferous epithelium. We also used freeze fracture to analyze the characteristics of tubulo-bulbar complexes, a known component of apical ectoplasmic specializations. Also, these different approaches 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 beta-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 beta-actin network, the junctional complexes of the blood-testis barrier and the ectoplasmic specializations were detected at different stages of the seminiferous cycle.

Distribución de los mastocitos en las glándulas salivales mayores de rata

Los mastocitos son células del tejido conectivo ampliamente distribuidas en la mucosa digestiva y respiratoria, especialmente cerca de sitios de respuesta inmune. El presente estudio se efectuó con el propósito de evaluar la distribución de los mastocitos en las glándulas salivales mayores (parótida, submaxilar y sublingual) de rata. Las muestras de tejido glandular fueron incluidas en parafina y los cortes histológicos obtenidos se colorearon con Azul alcian-safranina y Azul de Toluidina. Posteriormente se efectuó la cuantificación de mastocitos/mm2 considerando dos áreas glandulares: el estroma intralobulillar y el interlobulillar. Los resultados no muestran variaciones significativas en la población de mastocitos al comparar las tres glándulas (p>0,05), pero si se encontró una mayor presencia de mastocitos en relación con la vía excretora principal. Los resultados en conjunto sugieren una activa participación de los mastocitos en los mecanismos de detección de antígenos que ingresan a las glándulas salivales y su estrecha relación con otras células captadoras de antígenos como las células dendríticas.

Mast cells (MT) are connective tissue cells widely distributed throughout the body, especially in immune mucosal response sites like the digestive and air way tract. The aim of the present study was to find the number and the pattern of distribution and possible differences in mast cell population present in the mayor salivary glands (parotid, submandibular and sublingual glands) of rats. Fragments from salivary glands were collected, processed an included in paraffin wax, cut and stained with alcian blue-safranin and toluidine blue. The total number of MT was counted to estimate the mm² population from both intralobulillar and interlobulillar stroma tissues. Statistical analysis showed not significant differences (p> 0.05) between the three analysed glands. Numerous mast cells were located around salivary secretory ducts, in close association The results suggest that MT play a relevant role in salivary antigen detection and that there is a close cooperation with other antigen professional presenting cells like dendritic cells.