Postnatal renal tubule development in inbred indigenous rabbit (Oryctolagus Cuniculus): A histological and immunohistochemical analysis

This study investigates postnatal renal tubules development in inbred indigenous rabbits (Oryctolagus cuniculus), examining histological, histochemical, morphometric, and immunohistochemical characteristics from birth to 40 days old. Fifty rabbits were categorized into five age groups based on postnatal days (PNDs) 1, 10, 15, 30, and 40. Kidneys were fixed, processed, and sectioned for hematoxylin and eosin and PAS-Alcian Blue staining, followed by microscopic examination. Immunohistochemical analysis used Anti-Lgr5 antibody to detect stem cells. Morphometric measurements were taken manually with an USB digital camera. The findings indicate that while renal tubules in one day aged rabbits had completed histogenesis through the embryonic life, they continued to develop until PND 40. A regular decrement in the epithelial height and lumen diameter of proximal and distal convoluted tubules (PCT and DCT) was observed, with PCT showing reductions of 2.3-fold and 2.1-fold, respectively, and DCT displaying a 3.5-fold decrease in lumen diameter and a 1.5-fold reduction in epithelial height. Intriguingly, Lgr5 expression, absent in PCT and DCT, was detected in interstitial tissues surrounding the LoH, with moderate expression at PND 1, gradually declining thereafter. These findings provide valuable insights into renal tubule maturation and lay a foundation for future research in renal development and regenerative medicine.