Histogenesis Of Human Fetal Renal Medulla

ABSTRACT

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