Histogenesis of Human Fetal Renal Medulla

Abstract

Histogenesis of kidney gives knowledge regarding histological maturity of kidney and its functional status at the given gestational age. Kidney is developed from two parts, metanephrogenic blastema and ureteric bud. Metanephrogenic blastema gives origin to secretory part i.e. nephron while ureteric bud forms the collecting part i.e. collecting tubules and ureter. Both these parts fuse with each other and the development becomes complete. Materials and Methods: 50 aborted human fetuses between 13-36 weeks of gestational age were used for this study with no obvious congenital anomalies. The 2-3 mm thick cut sections of both kidneys were taken, processed and Paraffin blocks were prepared. 5-7 micron thick sections were taken with rotary microtome, mounted and then stained with Haematoxylin and Eosin. Microscopic features were observed in low and high power and then documented. Results and Discussion: Differentiation between cortex and medulla was seen from 16-18 week onwards. The medulla with collecting ducts, thick and thin segment of loop of Henle became well differentiated from 16 week onwards. Vascularity of medulla increased with increase in gestational age while connective tissue decreased with increase in gestational age. Renal pelvis was lined by transitional epithelium.