Chromogranin-A expression in the bovine testis

摘要

Chromogranin-A (CgA) is the most distributed member of the granin family. Chromogranins are soluble anionic glycoproteins, found in the majority of the neuroendocrine and neural cells, co-stored with other endocrine substances (like insulin, glucagon, FSH and LH or NPY) in secretory granules. Outside the cell, it has been suggested that this peptide or one of its fragments, obtained by proteolytic cleavage, could act in an autocrine or paracrine way, regulating either the cell function or the contractibility of vascular segments. The purpose of the present study is to determine the distribution of chromogranin-A in the structures of the bovine testis. Immunohistochemical analysis was performed employing the biotin-streptavidin-peroxidase immunostaining technique in tissue specimens obtained at a local abbatoir. A CgA expression was found in the germinal epithelium at several stages of differentiation. Generally the strongest positive reaction was consistently observed in the basal compartment of the seminiferous tubules, with spermatogonia presenting a dense granular immunostaining pattern; a less intense reaction was also consistently recorded in type II spermatocytes and in round spermatids, which showed a more scattered disposition of CgA-positive granules. Clusters of Leydig cells also displayed a faint and homogeneous cytoplasmatic immunoreactivity for chromogranin-A. These results demonstrate a widely distribution of CgA-positive cells in the organism, and its presence in the testis raises the possibility of its participation in the cohort of local factors involved in the regulation of spermatogenesis.