Estudo estrutural da bexiga em fetos humanos normais e com síndrome de Prune Belly

Abstract

Prune Belly syndrome is a disorder characterized by deficiency of the abdominal muscles, malformations of the urinary tract and bilateral cryptorchidism. The objective of this thesis is to study the bladder structure of fetuses with Prune Belly syndrome (PBS). We studied three bladders obtained from three male fetuses with PBS and seven bladders obtained from seven male fetuses without anomaly. The gestational age of the fetuses was determined in weeks post conception (WPC), according to the foot-length criterion. After the measurements, the fetuses were carefully dissected with the aid of a stereoscopic lens with 16/25X magnification. The abdomen and pelvis were opened to identify and expose the urogenital organs. Each bladder was dissected and embedded in paraffin, from which 5µm 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). Also, 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 and a p-value < 0.05 was considered statistically significant. The PBS fetuses ranged in age from 17 to 31 WPC and weighed between 240 and 2150g. The fetuses from the control group ranged in age from 12 to 35 WPC, and weighed between 430, and 2860g. 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 the 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 compared to the PBS fetuses. 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 Prune Belly syndrome.