| Objective: To establish an animal model of hypospadias induced by acute injury in New Zealand rabbits,and to study the gross morphology and ultrastructural characteristics of new urethra after urethroplasty with three kinds of conserving urethral plate urethroplasty(CUPU),including tubularized incised plate urethroplasty(TIPU),flip—flap urethroplasty(Mathieu)and onlay island flap urethroplasty(Onlay),so as to provide reference for clinical surgical decision-making.Methods: Sixteen male New Zealand rabbits were randomly divided into control group(n = 4)and intervention group(n = 12).The intervention group was divided into TIPU group(n = 4),Mathieu group(n = 4)and Onlay group(n = 4).In the intervention group,part of the urethral tissue was removed to form an animal model of hypospadias with acute injury.TIPU,Mathieu and Onlay were used for urethroplasty.Two weeks after operation,the wound healing was observed,and the new urethral tissue was stained with hematoxylin-eosin(HE)and Masson staining to study the general morphological differences under different surgical procedures.At the same time,Vimentin and transforming growth factor-β 1(TGF-β 1)were detected by immunohistochemistry,and the ultrastructural features were observed by transmission electron microscope.The urethral tissue was directly removed from the urethra for the above experiment without intervention in the control group.In this study,the positive expression results of immunohistochemistry were calculated by Image-Pro Plus 6.0.The other data were analyzed by SPSS 25.0.The difference was statistically significant if P<0.05.Results:(1)Establishment of animal model of hypospadias: 12 New Zealand rabbits with acute injury hypospadias were successfully established by surgery.(2)Gross observation of new urethra at 2 weeks after operation with three kinds of CUPU: The appearance of urethra in TIPU group and Mathieu group was similar to control group,showing pink color and less scar.And the urethral scar in Onlay group was more serious,the color was dark and the local blood circulation was poor.(3)Histological examination and transmission electron microscopic observation: HE staining and Masson staining showed that the arrangement of collagen fibers in TIPU group was slightly disordered,which was generally close to that of the control group,and the number of submucosal microvessels increased;In Mathieu group,the arrangement of collagen fibers was disordered,the infiltration of inflammatory cells was more serious,and some immature collagen fibers were formed;In Onlay group,the inflammatory cells infiltrated seriously,collagen fibers increased and became dense,and arranged disorderly.Immunohistochemical analysis showed that the expression of Vimentin in TIPU group was significantly lower than that in Mathieu group and Onlay group,and there was no significant difference between Mathieu group and Onlay group(P=0.387).The expression of TGF-β 1 in TIPU group was significantly lower than that in Mathieu group and Onlay group,and the expression in Mathieu group was also significantly lower than that in Onlay group(P=0.031).Transmission electron microscope observation showed that fibroblasts in TIPU group disappeared,separated from surrounding cells,and apoptotic bodies were formed;Endoplasmic reticulum increased in Mathieu group,synthesis and secretion were exuberant;Autophagy was enhanced in Onlay group.Conclusion: 1.The rabbit hypospadias animal model was successfully established by surgery,and 2.There were differences in healing between tissues from different sources,so for mild to moderate hypospadias under the same anatomical conditions,a single tissue source should be used as far as possible to repair the urethra.3.The tissue source of urethroplasty after TIPU is single,which accords with the structure of normal urethra,the new urethra healed well,the collagen fibers arranged neatly,the expression of Vimentin and TGF-β 1 was low,and fibroblasts showed apoptosis,so it is suggested that this procedure should be the first choice.4.But in some cases,it is recommended to use Onlay or Mathieu procedure because urethroplasty can not be done only by one kind of tissue. |
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