Structural And Ontogenetic Study of The Urachus in Human Fetuses

Abstract

Purpose The objective of this work is to make a ontogenetic and structural study of the urachus in human fetuses. Material and Methods We studied 40 human fetuses (20 male and 20 female), evaluated with regard to the foot length, crown-rump length and body weight. The urachus was dissected and embedded in paraffin, from which 5μm thick sections were obtained and stained in Masson tricrome. The images were captured with Olympus BX51 microscopy and Olympus DP70 camera. The Stereological analysis was done with the software Image J Pro using a grid to determine volumetric densities (Vv). For the biochemical analysis, tissue samples were fixed in acetone, delipidated, and dried. A hyroxyproline assay was then performed and total collagen content was expressed as μg hyroxyproline per mg dry tissue. Means were statistically compared using the ANOVA and Unpaired T test (p Results Gestational age ranged from 12 to 25 weeks post conception (WPC). Quantitative analysis documented a increase in Vv smooth muscle cells in male urachus (23.02%), when compared to female (18.43%), there was no statistically significance (p = 0.1478). Quantitative analysis documented a increase in Vv of connective tissue in female urachus (67.64%), when compared to male (58.38%), there was a statistically significance (p = 0.0439). Total collagen concentration in male urachus (mean = 45656μg/mg), and in female (mean = 42308μg/mg) did not differ significantly (p = 0.5912). As higher was the gestational age, smaller was the urachal lumen area. In 13WPC fetuses the urachal lumen was 16301μm 2 and in 17WPC fetuses the urachal lumen area was 1676μm 2 . The urachal lumen was closed from the 18thWPC in male and female Conclusions In this work we determine that the urachal lumen was closed from the 18WPC in all fetuses. The data obtained in the present study can be used as base knowledge related to the development of the urachus.