Histological and histochemical study on the mesonephric kidney of Pelophylax bedriagae (Anura: Ranidae)

The purpose of this study was to determine the histological structure of the kidney of Pelophylax bedriagae and the distribution of hyaluronic acid (HA) in the kidney tissue. The kidneys of P bedriagae are long, brown, ribbon-like structures covered with connective tissue. Nephrons, the functional units of the kidney, consist of the renal corpuscle, proximal and distal tubules, collecting tubule, and collecting duct. The renal corpuscle is composed of the glomerulus and Bowman's capsule. There is no structure similar to Henle's loop, which is found in higher vertebrates. The visceral layer of Bowman's capsule is composed of podocytes surrounding the glomerular capillaries. The parietal layer of Bowman's capsule is lined with a simple squamous epithelium. The proximal tubule is formed by cubic epithelial cells with a brush border, and the distal tubule is covered with a simple cubic epithelium without a brush border. The collecting ducts consist of columnar or cubic cells, and they are larger than the proximal and distal tubules. Many melanomacrophage centers were observed in the kidney parenchyma. The localization of HA was determined to be in the interstitium surrounding the collecting ducts. HA probably plays a significant role in renal water handling and electrolyte balance due to its ability to retain water and bind cations.