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.