RESUMO
OBJECTIVE: To evaluate the epithelial thickness, number of vessels, amount of collagen and muscular fibers of the bladder and urethra of castrated adult female rats during the time between castration and the beginning of the administration of synthetic conjugated estrogen. METHOD: 118 adult female rats were divided into four groups: Group I (n = 30): noncastrated female rats; group II (n = 30): female rats treated with synthetic conjugated estrogen in the dose of 50 microg/animal/day for 28 days, beginning immediately after castration; group III (n = 28): female rats treated with synthetic conjugated estrogen, 50 microg/animal/day for 28 days, beginning 30 days after castration: group IV (n = 30): female rats sacrificed after 30 days of castration. The histology of the bladder wall and the medium-third of the urethra wall were evaluated after flushing with hematoxylin-eosin and picrosirius for morphometric analysis. RESULTS: It was verified that the epithelial thickness in groups II and III were similar whereas in groups I, II and III the thickness of the bladder and also the urethra were larger than in group IV. Concerning the bladder groups I and II were similar. In group I the urethra was superior than in groups II and III. In relation to the number of vessels and muscular fibers, groups I, II and III were similar to each other and superior to group IV in the bladder and urethra. The amount of collagen was similar in groups I, II and III and inferior in group IV in the bladder and in the urethra. CONCLUSION: Independent of the time of estrogen administration (immediate or within 30 days) after castration, the thickness of the epithelium, the number of vessels, amount of collagen and muscular fibers were similar. The female rats with estrogen replacement presented significantly larger thickness of the epithelium, number of vessels and muscular fibers, and a smaller amount of collagen in the bladder and urethra in relation to the castrated group. Finally, estrogen therapy (immediate and 30 days after castration) reverted the effects of the estrogen deficiency in the vessels, collagen and muscular fibers, the bladder and of the urethra when compared to the group of castrated female rats, thus becoming similar to noncastrated animals.
