Histomorphology of the urethral process of the goat (Capra hircus).

The urethral process of the goat was an extension of the pars spongiosa of the male urethra. The erectile (cavernous) tissue of the urethral process was a continuation of the corpus spongiosum penis. The epithelium lining the urethra was stratified transitional. Two compact fibrocartilaginous strands were embedded in the erectile tissue, which were absent towards the tip of the urethral process. Smooth muscle was absent in the tunica mucosa-submucosa of the urethral process. The tunica mucosa-submucosa was richly supplied with blood vessels and nerves and it may be assumed that the urethral process is a sensory structure. Large cavernous sinuses, within the erectile tissue, were lined by endothelial cells. There was a circular fibroelastic layer enclosing the entire corpus spongiosum penis to withstand expansion of the erectile tissue during erection and copulation. The surface epithelium lining the urethral process was stratified squamous. A few connective tissue papillae were observed evaginating into the surface epithelium.