Scanning electron microscopic observations on the epithelium of the human spongy urethra.

The human spongy urethras of individuals submitted to emasculation because of glans carcinoma have been studied by means of scanning electron microscopy. The luminal surface of the organ shows longitudinal folds and small glandular openings, surrounded by epithelial elements arranged in form of rosettes. Spermatozoa, partially degenerated, adhere to the epithelium. The slightly prominent apices of the superficial epithelial cells are more or less polygonal in shape and covered with short microvilli among which small granules as possible morphological expression of a secretory activity are detectable. Only seldom microplicae, intermingled with microvilli, can be observed. Additionally, some apices appear swollen and protrude into the lumen. Such a pattern may be escalated so that a cell seems to transform itself into a globular mass and then is expulsed from the epithelial surface. Sometimes an epithelial cell appears empty of its contents: only the crumpled plasmalemma remains. This may represent the morphological expression of an apocrine or holocrine secretory activity of the superficial epithelium. In few cases, the proximal portion of the spongy urethra shows small groups of ciliated elements.