[Urethroplasty of the free colonic mucosa in rats. Preliminary study of the use of appendicular mucosa].

The various tissues used as free grafts in urethroplasties are associated with a high incidence of fistulae and strictures. The search for a new, more effective substitute had led the authors to study the possibility of using a new type of mucosa: appendicular mucosa. The size and cylindrical structure of the appendix and its easy resection make it an original and adapted urethral substitute. As most animals do not possess an appendix, an animal model of urethroplasty with colic mucosa has been used. A segmental distal urethrectomy has been performed on 40 rats, 14 had a simple urethral stent without any urethroplasty (Group I), for 7 wi performed the urethroplasty with a collagen tube (Group II) and for 19 an urethroplasty with free colic mucosa was performed (Group III), 3 to 6 weeks later, a macroscopic and microscopic study were realised. In group I and II the urethral duct developed a fibrosis and all rats had a severe stenosis when the stent went out. In those two groups, a urinary fistula has been developed in all rats except one. In group III, a neo-urethra was found. Under light microscopic examination a typical urothelium was observed in the mid and distal section and a keratinized squamous epithelium on the distal section. The results of the preliminary study let us believe that the digestive mucosa may be used for urethroplasty. Before we can propose the appendix mucosa in human surgery, it will be useful to perform sooner histological examination, then the genesis of the neo-urothelium should be understood.