Histological analysis of urethral healing after tubularized incised plate urethroplasty

PURPOSE: Tubularized incised plate urethroplasty has rapidly gained popularity for treating hypospadias. It is presumed that healing occurs with the postoperative migration of epithelial cells into the incised urethral plate. We describe the time course and histology of the healing urethral wound in an animal model after dorsal incision and stenting. MATERIALS AND METHODS: A procedure was developed for use in an immature porcine model. The ventral aspect of the urethra was opened and a dorsal incision was made in the urethra to the level of the corpus spongiosum. The urethra was then catheterized and closed ventrally. Animals were sacrificed at intervals of 1, 2, 3, 5, 7, 14 and 21 days. Slides were made from multiple cross sections taken from each penis, and stained with hematoxylin and eosin, and Masson trichrome before analysis. RESULTS: Migration of epithelial cells into the dorsal epithelial defect was evident on postoperative day 2 with apparent complete re-epithelialization by postoperative day 5. Regions of increased fibroblastic activity were observed in the subepithelial stroma below the incised area on postoperative day 3 and early collagen deposition was noted in these areas when stained with Masson trichrome. These areas appeared to organize and by postoperative day 21 there was little evidence of increased fibroblastic activity or excess collagen deposition. CONCLUSIONS: Urethral healing after incision and tubularization over a catheter in our model occurred through normal re-epithelialization without excess collagen deposition or scarring.