Figure 1: Histopathology changes on re-epithelialization of wound healing in canine prostatic urethra after two-micron laser resection of the prostate. ( a ) At 3 days, prominent proliferation of the epithelium from acinar and ductal prostatic epithelium was observed under coagulation necrosis (arrows) (×200). ( b ) At 1 week, prominent proliferation of the epithelium with distinct squamous metaplasia originating from the underlying prostatic acinar and ductal tissue (black arrows), the proliferating epithelium extended to the lumen of the cavity with focal re-epithelization of the surface (white arrows) (×100). ( c ) At 1 week, adjacent to the transitional epithelium of the bladder neck margin, inflammatory exudate was noted (arrow) (×200). ( d ) At 2 weeks, marked proliferation of the epithelial glandular elements, with notable squamous metaplasia, extended to the surface of the cavity with more regenerative epithelium (×100). ( e ) At 3 weeks, re-epithelialization was basically complete (×100). ( f ) At 4 weeks, the regenerative epithelium lining the central cavity appeared normal with a distinct layer of umbrella cells (×200).