Plasminogen activator and inhibin in the human testis. An immunohistochemical investigation.

It is generally accepted that Sertoli cells are the main source of active proteins in the human testis, these proteins can act by autocrine and/or paracrine mechanism, modulating both the gametogenic and the endocrine function of the male gonad. As to the Plasminogen Activators (T-PA, U-PA) the immunocytochemical reactivity was detectable in the Sertoli cells and in some Leydig cells. A positivity in spermatocytes and early spermatides appeared to be in relation to the stage of the cycle of the seminiferous epithelium. Inhibin was studied in foetal as well in prepubertal and adult life. The positivity for alpha human and alpha porcine subunits was intense only in the interstitial cells at 12-15 weeks of foetal life. Afterwards the staining was detectable in the Sertoli cells while it decreased in the interstitial cells. In prepubertal life, only the Sertoli cells were stained. In adult life, at the light microscopic level the Sertoli and Leydig cells were positive as well as the spermatocytes. At the electron microscopic level, coated pits and vesicles containing labelled golden particles were shown in both Sertoli cells and spermatocytes, suggesting a paracrine activity of the substance.