RESUMO
AIMS: To study the bladder structure of fetuses with prune belly syndrome (PBS). METHODS: We studied three bladders obtained from three male fetuses with PBS and seven bladders from seven male fetuses without anomalies. Each bladder was dissected and embedded in paraffin, from which 5 µm thick sections were obtained and stained with Masson's trichrome (to quantify connective tissue and smooth muscle) and picrosirius red with polarization (to observe collagen). Immunohistochemistry with tubulin (Tubulin, beta III, Mouse Monoclonal Antibody) was applied to observe the bladder nerves. The images were captured with an Olympus BX51 microscope and Olympus DP70 camera. The stereological analysis was done with the Image Pro and Image J programs, using a grid to determine volumetric densities (Vv). Means were statistically compared using the Mann-Whitney test (P < 0.05). RESULTS: Quantitative analysis documented that smooth muscle fibers were significantly smaller (P = 0.04) in PBS fetuses (9.67% to 17.75%, mean = 13.2%) compared to control group (13.33% to 26.56%, mean = 17.43%). The analysis of collagen fibers showed predominance of green in the control group, suggesting collagen type III presence, and predominance of red in the in PBS fetal bladders, suggesting collagen type I presence in this group. The qualitative analysis of the nerves with immunohistochemistry with tubulin showed predominance of nerves in the control group. CONCLUSION: The bladder in PBS had lower concentrations of smooth muscle fibers, collagen type III, and nerves. These structural alterations can be one of the factors involved in urinary tract abnormality such as distended bladder in patients with PBS.