Ultrastructure of testes and excurrent ducts in the bonnet monkey (Macaca radiata).

The testes and excurrent ducts of four bonnet macaques (Macaca radiata) were examined using scanning and transmission electron microscopy. The three layers of contractile and connective tissue composing the tunica albuginea, and the multilayered tunica propria of the seminiferous tubules were similar to that of man. Spermatids project from the epithelium or are found free in the lumen. The stages of the cycle of the germinal epithelium in the bonnet macaque were similar to that in other macaques. The epithelium of the rete testis consisted of thin brush-bordered cells, whereas the epithelium of the efferent ducts consisted of tall, prismatic or cylindrical cells lined by kinocillia or short stereocilia and basal cells. The height of the epididymal epithelium and lumen diameter was maximal in the caput region and minimal at the cauda. Spermatozoa were found among clusters of stereocilia. The epithelium of the vas deferens showed gradual transition from the stereocilia covering typical of the epididymis to that of a shorter, apical microvilli covering.