Microscopic anatomy of the scrotum, testis with its excurrent duct system and spermatic cord of Didelphis azarae.

The authors give a description of the microscopic anatomy of the scrotum, testis and its excurrent duct system and the structures of the spermatic cord. The scrotal skin of Didelphis azarae is hairy with the surface marked by shallow grooves and spotted with black pigmented areas. Clear cells and mitotic figures are frequently seen in the basal region. The sweat glands are tubular, apocrine, with alcian-blue- and PAS-positive secretion, presenting large myoepithelial cells. The tunica dartos is poorly developed. The tunica vaginalis is constituted by three layers, presenting patches of melanocytes in variable extensions. The tunica albuginea is composed preponderantly of collage and thin elastic fibers without muscle fibers. The interstitial tissue presents connective cells and a large number of Leydig cells. Mast cells were not observed. The tunica propria of the seminiferous tubuli is fibroelastic with two or three layers of elongated cells. The straight tubuli are divided into three different portions lined by epithelium with variable height. These tubuli at the mediastinum join each other to form a single duct near the cranial pole of the testis. The extratesticular segment of the efferent duct divides initially into two and then into three or four smaller flexuous ductuli to constitute the head of the epididymis. The spermatic cord shows a well-developed cremaster muscle. A collagenous fibrous band separates the muscle from the deferent duct and vessels. Mast cells are observed among the muscle fibers of the cremaster and the tunica adventitia of the blood vessels.