Defeitos do tubo neural causam alterações estruturais no ureter? Estudo em fetos humanos

Abstract

Anencephaly is the most severe neural tube defect. Morphology of the ureter in anencephalic fetuses is unknown. The objective of this paper is to analyze the structure of the ureter in normal and anencephalic human fetuses (AHF). We studied 16 ureters from 8 fetuses without congenital anomalies (4 male and 4 female) aged 16 to 27 weeks post-conception (WPC) and 14 ureters from 7 AFH (4 male and 3 female) aged 19 to 33 WPC. The ureters were dissected and embedded in paraffin, from which 5µm thick sections were obtained and stained in Masson trichrome, to quantify smooth muscle cells (SMC) and to determine the ureteral lumen area, thickness and diameter. The samples were also stained in Weigert Resorcin Fucsin (to observe elastic fibers) and Picro-Sirius Red with polarization and immunohistochemistry analysis of the collagen type III fibers to observe collagen. Stereological analysis of SMC was performed in sections. Data were expressed as volumetric density (Vv-%). The images were captured with Olympus BX51 microscopy and Olympus DP70 camera. The stereological analysis and the ureteral lumen area, thickness and diameter were done using the software Image Pro and Image J. Means were statistically compared using the unpaired t-test (p < 0.05). The ureteral epithelium was well preserved in the anencephalic and control groups without differences in the two groups. We did not observe elastic system fibers in any ureter analyzed. Smooth muscle concentration (Vv) did not differ significantly (p=0.4413) in AFH (12% ± 1.628) and control group (13.51%± 0.9231). The ureteral lumen area was significantly smaller (p=0.0341) in AFH (6365µm ± 1282) when compared to control group (20170 µm ± 5480). The ureteral diameter was significantly smaller (p=0.0294) in AFH (166.7µm ± 10.99) when compared to control group (240 µm ± 26.6). The ureteral thickness was significantly smaller (p=0.0448) in AFH (30.57µm ± 2.034) when compared to control group (47.49µm ± 7.453). Type III collagen was observed in a higher quantity in ureters of AFH. Structural ureteral alterations in AFH were significant in our study. The ureter in fetuses with anencephalia showed more type III collagen concentration, smaller diameter, area and thickness. Ureteral nerves in AFH could be modified due to cerebral lesions with consequent brain control damage in ureteral nerves. This could lead to structural alterations in anencephalic ureter fetuses.