Light and electron microscopical observations on the male excurrent duct system of the common shrew (Sorex araneus).

In sexually active common shrews (Sorex araneus) the rete testis is a simple sac-like structure situated superficially between the equator and the anterior pole of the testis, and its epithelium glycogen-rich cells. In the ductuli efferentes, the tight junctions of the epithelial cells are poorly developed. The epididymis can be divided cytologically into initial, middle and terminal segments, and some variations are apparent in the fine structure of the principal cells throughout the duct. In the initial segment and in the most proximal part of the middle segment, mitochondrion-rich cells occur sporadically in the epithelium. The ductus deferens is divided into three anatomical regions, a tortuous pars epididymica, a straight middle portion, and an ampullary region. The distal half of the straight portion is distended, and appears to function, together with the terminal segment of the epididymis, as a sperm reservoir.