Anatomy and histology of penile deep dorsal vein: venous cushions and proximal "sphincter".

A sphincter-like structure was found at the base of the penis at the division of the crura surrounding the deep dorsal vein and, in instances of paired veins, around both veins. The deep dorsal vein in this anatomic region does not have a clear-cut adventitia or external wall. The venous lumen is stellate in cross sections, with much surrounding smooth muscle, nerve fibers, and connective tissue blending into the penile tissue external to the tunica albuginea. Further microscopic and gross studies of the deep dorsal vein in 10 specimens revealed consistently smooth muscle "polsters" the entire length of the vein, with the fibers directed in a longitudinal fashion. Photomicrographs of this structure are shown, and some theoretical notions about the function of this peculiar-appearing anatomic structure are described.