Endocrine cells in the excurrent duct system of the testis. An immunohistochemical analysis

A systematic search for endocrine cells in the excurrent duct system of the testis was carried out by means of histochemical and immunohistochemical techniques. A panel of antibodies against amine and polypeptide hormones was used. 80 specimens comprising representative areas of rete testis, ductuli efferentes, ductus epididymis and 30 examples of ductus deferens were investigated. Cells immunoreactive for serotonin were detected in four out of 110 specimens. They were invariably in normal-appearing ductuli efferentes. A salient feature was their rarity and focal distribution. We failed to detect any endocrine cells in other segments of the excurrent duct system and notably not among epididymal epithelium. It seems of interest that serotonin cells are specifically distributed throughout remnants of excretory mesonephric tubules in both males and females.