A Comparative Study on Kidney Morphology of Anatolian Ground Squirrels, Rabbits, and Rats

In this study, the kidneys of ground squirrels (hibernated and nonhibernated), rabbits, and rats were examined macro and microanatomically. Kidney morphology was investigated by stereo microscopy, light microscopy, and scanning electron microscopy. Triple and immunohistochemical staining were performed for light microscopic examinations. Cold crushing and takilon injection into the renal arteries were performed for scanning electron microscopic examinations. The course and branching of intrarenal capillaries and morphologic features from glomeruli to foramina papillaria were demonstrated. The location, position, shape, weight, and size of the kidneys of the three species studied were determined. Relative medullary thickness (RMT) and kidney index (Ki) values were calculated from the measurements. Based on the RMT values of the three species, it was concluded that they are mammals belonging to the semiarid and humid habitat category. The number of nephrons with long segments was high in the kidneys of all three species. Structural findings suggested that the rat may produce more concentrated urine than the ground squirrel, and the ground squirrel may produce more concentrated urine than the rabbit. The mean diameter of the renal corpuscles was 112.5 μm in the hibernated ground squirrel, 137.6 μm in the nonhibernated ground squirrel, 138.1 μm in the rabbit, and 137.8 μm in the rat. In hibernated ground squirrels, a narrowing of the cavum glomeruli and a decrease in renal corpuscle diameters were found. In contrast to ground squirrel and rat kidneys, rabbit kidneys showed the presence of species-specific subcapsular glomeruli. Immunohistochemistry (antinestin antibody) staining and scanning electron microscope (SEM) images revealed the structure of podocytes in detail. Species-specific area cribrosa configurations were detected in the renal papillae of the kidneys we examined. With this study, new renal morphological findings were obtained in ground squirrels, rabbits, and rats.