Normal Histology in the Fetal Renal Pelvis

Lee, Ahkie; Choi, Hwang

Abstract

In relation to the question, "Why congenital UPI obstructions are accompanied by more severe changes in structure and compliance of renal pelvis than the changes observed in adults?", there has been limited histological study of the normal fetal renal pelvis. In this study we documented the serial changes of collagen and smooth muscle component in the renal pelvis of 13 fetuses ranging in ovulatory age from 20 to 44 weeks using image analyzer. The thickness of lamina muscularis of renal pelvis was increased gradually according to increase of gestational period (range of thickness ; 68.0 - 420.8 um, R^2 = 0.67, P = 0.0004). The thickness of lamina propria was the same as lamina muscularis (range of thickness , 72.1 - 268.6 um. R^2 = 0.70, P = 0.0002). Additionally, there were progressive increases in the percent area of collagen fiber in lamina propria (range of percent area , 22.43 - 61.95%, R^2 = 0.41, P = 0.018) and the percent area of muscle in lamina muscularis (range of percent area ; 10.54 - 61.95%, R^2 = 0.43, P=0.015). In conclusion, these observations suggest that the underdevelopment of smooth muscle and collagen fiber in early gestational period are responsible for severe structural deformity in primary UPJ obstruction.