Experimental assessment of ureteral free autograft.

OBJECTIVE: To establish the sequence of ureteral events under ischemic and desvascularized conditions but without immunologic interference. MATERIALS AND METHODS: Sixty-two rats were divided into four groups. NU group (n 20) control group, normal ureter; SC group (n 15) only surgical control ureterolysis; NIAFG group (n 13) ureter used as non integrated autologous free graft; IAFG group (n 14): ureter used as integrated autologous free graft. Urographic, histologic and histomorphometric studies were performed. RESULTS: We established ureteral changes in the NIAFG and IAFG groups, compared to the control groups (NU, SC). Surgical findings and urographic assessment revealed normal peristalsis with no ectasia in some cases, and no ureteral fistulas or extravasations were found in the IAFG group. Histologic findings showed preservation of the architecture of the three normal layers. Histomorphometric studies showed that ureterolysis caused edema in the lamina propria, while changes in ureter free graft depended on whether the ureter was integrated or not. In the NIAFG group only the urothelial layers showed differences and in the IAFG group the ureteral wall appeared thicker. Histomorphometric studies showed preservation of the normal histologic structures in all cases. CONCLUSIONS: The rat ureter can be used as a free autologous graft and represents an experimental model for immunologic events. We may assume that the necrosis and fibrosis observed in transplanted ureters are secondary to rejection in some cases.

Experimental study of ureteral free grafts. IV. Histomorphometric study.

OBJECTIVES: The ureteral changes that occur when rat ureter is used as an autologous free graft were evaluated using histomorphometrical methods. METHODS: The normal values were determined in ureters from normal rats (NU group) and compared with those of a control group undergoing ureterolysis, as well as with two groups in which the ureter was used as an autologous free graft (in one of these groups the ureter was integrated into the urinary tract by anastomosis, whereas in the other group the ureter was not integrated). The main histomorphometrical parameters were thickness or length and surface or area. Thickness measurements were made using a micrometer. For area determinations, paper prints of light micrographs from each segment were measured using a Koizumi KP-90 digital planimeter. A non-parametric variance analysis (Kruskal-Wallis test) was used to compare the results. These results were compared with those of the Wilcoxon test. The results are expressed as different levels of alpha, (0.05, 0.01 and 0.001). RESULTS: When p < 0.01, there were practically no statistically different variables between NU and AU. Comparison of NU to SC and SC to AU showed only seven statistically different variables. Muscle layer thickness was different only when the comparison was made with the RUb group. When p < 0.001, RUa and RUb were not different, nor were NU and AU or SC and NU. Differences were observed between RUb and all the other groups. RUa was different from NU, SC, or AU in 3, 4 or 5 of the 18 variables analyzed. Most of the surface variables were significantly different in RUb in comparison to the other groups. There were also differences between RUa and NU, as well as between NU and SC, in the area of the lamina propria. CONCLUSIONS: Initial ischemia and denervation are not the cause of the observed changes, as these changes are different in both types of free graft. Histomorphometrical studies constitute a useful method in the assessment of differences between ureteral free graft groups. None of the histomorphometric findings is inconsistent with the use of the rat ureter as a free graft.

Experimental study of ureteral free grafts. III. Histological findings.

OBJECTIVES: To analyze histological findings in rat ureter used as free autologous graft and compare them with two controls. METHODS: They were randomly distributed into four groups: NU group (n = 20), ureter from healthy rats; SC group (n = 15), ureter from rats undergoing ureterolysis, the surgical control group; AU group (n = 13), rats with ureter used as ANIFG (autologous non-integrated free graft); RU group (n = 14), rats with ureter used as AIFG (autologous integrated free graft). For the histological study, ureteral cross sections were obtained (A proximal, B middle, and C distal) and kidney (K) was studied. In addition, in the RU group, we obtained one cross section above the proximal suture (D), one below the distal suture (E), and two longitudinal sections of the surgical anastomoses (F and G). RESULTS: The results showed a histological similarity between the NU, SC and AU groups and an apparent viability of all RU group ureters in which necrosis has not been found. SC group: Mild edema could be noted in the lamina propria in some of the sections. None of the three ureteral layers showed any fibrosis or other lesions. AU group: All layers were preserved. The urothelium showed changes from mild hyperplasia to a wider area of denudation. Some of the sections showed mild fibrosis in the lamina propria. Nearly all sections showed an increased number of blood vessels in comparison to the NU group. Necrosis, fibrosis or loss of ureteral lumen were not usually observed. RU group with correct functional result (RUa): This group consisted of seven cases. The three layer structure was preserved, although some sections showed some ureteral disorganization. Three cases showed foci of fibrosis in the lamina propria. Some ureteral segments had abundant subepithelial blood vessels. The muscle layer was also preserved, with increased vasculature and in some cases partial fibrosis. The RU group with poor functional results comprised six animals. All the ureteral layers could be identified, although they had more abnormalities and "disorderly" appearance than the RUa. CONCLUSIONS: Rat ureter can be used as a free autologous graft. Both AIFG and ANIFG can be utilized as homologous grafts in order to study ureteral immunological changes. When the ureter was used as ANIFG, no significant necrosis or fibrosis were observed and only a slight reduction in diameter was noted. The AIFG graft can result in ureteral integration that allows normal function.

Histological and urographic findings in the autotransplanted ureter without kidney in dogs: preliminary report.

We took 7 dogs to undergo thorough autotransplant of the ureter as an autologous nonvascularized free graft, after having obtained good results with rats. The steps followed in these 7 dogs were the removal of a 10- to 12-cm segment of the ureter and the replantation of the same segment to the same animal. We must point out that both anastomoses were performed with interrupted sutures. Although some complications such as stenosis occurred, urographic studies showed that some animals kept their renal function for over 8 months after autotransplantation. Using contrast, we were able to observe the ureter. Similarly, we observed peristaltic waves on the ureters which were always dilated. Histologic studies showed preservation of the ureteral layers with hyperplasia of the ureteral mucosa, greater or lesser degree of submucosal fibrosis, and a variable degree of hyperplasia or muscular atrophy. Extensive areas of bone metaplasia were observed in some animals.