Macroscopic and histological evaluation of tunica vaginalis dorsal grafting in the first stage of Bracka's urethroplasty: an experimental study in rabbits

OBJECTIVE To evaluate the use of tunica vaginalis as a dorsal free graft in the first stage of Bracka's urethroplasty in a rabbit animal model using macroscopic and histological analysis. MATERIAL AND METHODS Surgery was performed on 16 rabbits, divided into four groups of four according to the number of weeks after surgery at which they were killed (2, 4, 8 and 12 weeks). The penile urethra was removed and only the ventral aspect of the urethra was reconstructed using a tunica vaginalis free graft dorsally fixed in the corpora cavernosa. Epithelial, inflammatory and fibrotic changes in the graft were evaluated macroscopically then histologically at the point when each rabbit group was killed. RESULTS Macroscopic evaluation showed good graft uptake with minimal retraction (P > 0.05). Histological evaluation showed a reduction in the inflammatory process during the first 4 weeks, after which inflammation stabilized. The mesothelium was partially healed at 2 and 8 weeks with a metaplasia defined by a stratified squamous, non-keratinized lining. The grafted area was thinner than the surrounding penile skin and similar to urothelial native epithelium. CONCLUSION Tunica vaginalis used as a free graft placed dorsally on the corpora cavernosa in the first stage of Bracka's urethroplasty shows good tissue integration and develops into a stratified non-keratinized epithelium (metaplasia) without significant retraction, despite exposure to the external environment.