Early events in stricture formation in the guinea pig urethra.

The early stages of urethal stricture formation have been examined by light and electron microscopy after injury of the anterior urethra in the guinea pig. It was found that initially an ulcerated surface formed which was subsequently covered by simple then stratified squamous epithelium. The tissue of the stricture contained elongated myofibroblasts and clumps of multinucleated giant cells. It is suggested that the myofibroblasts are responsible for the formation of the stricture and that the giant cells may be involved in continued collagen synthesis.