Study of Histogenesis of Human Fetal Renal Medulla by Using Masson’s Trichrome and PAS Stains

Introduction: Histogenesis of the human fetal kidney is the histological study of the maturity of the kidney at a given gestational age. Embryologically, the kidney is derived from the ureteric bud and the metanephric blastema. The ureteric bud forms the collecting part, and the metanephric blastema forms the secretory part. The details of the microscopic development of the kidney are not described in various textbooks of embryology. Methodology: 50 aborted human fetuses between 13 to 36 weeks of gestational age without any gross congenital anomalies were included in the present study. Paraffin blocks of the cut sections of both kidneys were prepared. Slides of 5–7 micron-thick sections stained with Masson’s trichrome (MT) and Periodic acid-schiff (PAS) stains. Results and Conclusion: From 16 weeks onwards, the medulla showed well-differentiated collecting ducts, thick and thin segments of the loop of Henle. The amount of connective tissue decreased, and the vascularity of the medulla increased with an increase in gestational age. The transitional epithelium lining the renal pelvis was appreciated from 16 weeks onwards. KEYWORDS: Histogenesis, Kidney, Renal medulla, Gestational age, Masson’s Trichrome stain, PAS stain.