The Histological Changes Of Autogenous Oral Mucosa And Penis Flap After Transplantation To Rabbit’s Urethra

Objectives:The purpose of this study is to observe and compare the histological changes of oral mucosa and penile flap after urethral transplantation in rabbit urethra defects models to analyze the feasibility and differences of the two commonly used urethra replacement grafts after urethra transplantation.Material and method:24 male New Zealand rabbits were randomly divided into three groups: oral mucosa group,penile flap group and control group.Each rabbit was induced a urethral defect in ventral urethra.The urethral defects were repaired with autologous free buccal mucosa in the oral mucosa group.The urethral defects were repaired with penile flap in the penile flap group.Every 2 rabbits of each group were performed urethrography and then killed for harvesting the penises in postoperative one months,two months,three months and four months.Histological chromogenic sections of the specimens were observed under optical microscope.The image j software was used to semi-quantitatively analyse the collagen content and expression of biochemical indexes of the specimens.SPSS 22.0 statistical software was used to process the experimental data.Results: All experimental animals were operated successfully.All animals in the control group had urethral stricture or urethral fistula.Two rabbits formed urethral diverticulum and one rabbit developed urethral fistula in the penile flap group.None of the animals in the oral mucosa group had surgical complications.Histological analysis found that the expression of transforming growth factor-β1(TGF-β1)was lower in the oral mucosa group than it in the penile flap group(p<0.01).The expression level of α-smooth muscle actin(α-SMA)in the oral mucosa group was lower than it in the penile flap group(p<0.01).The expression level of platelet endothelial cell adhesion molecule(PECAM-1/CD31)in the oral mucosa group was lower than it in the penile flap group(p<0.05).And there was no significant difference in the content of collagen fibers between the oral mucosa group and the penile flap group(p=0.442).Conclusion: Compared with penis skin,the fibrosis activity of buccal mucosa after transplantation is relatively weak and buccal mucosa has a trend into the normal urethral mucosa,which is more suitable for replacing the urethra.High level of inflammation,lack of tissue vascularization and increased fibroblast activity may be the pathogenesis of urethral stricture after urethral reconstruction.