Stereological assessment of normal Persian squirrels (Sciurus anomalus) kidney

The functions of the mammalian kidney are closely related to its structure. This suggests that renal function can be completely characterized by accurate knowledge of its quantitative morphological features. The aim of this study was to investigate the histomorphometric features of the kidney using design-based and unbiased stereological methods in the Persian squirrel (Sciurus anomalus), which is the only representative of the Sciuridae family in the Middle East. The left kidneys of five animals were examined. Total volume of the kidney, cortex, and medulla were determined to be 960.75 +/- 87.4, 754.31 +/- 77.09 and 206.1 +/- 16.89 mm(3), respectively. The glomerular number was 32844.03 +/- 1069.19, and the total glomerular volume was estimated to be 36.7 +/- 1.45 mm(3). The volume and length of the proximal convoluted tubule were estimated at 585.67 +/- 60.7 mm(3) and 328.8 +/- 14.8 m, respectively, with both values being greater than those reported in the rat kidney. The volume and length of the distal convoluted tubule were calculated at 122.34 +/- 7.38 mm(3) and 234.4 +/- 17.45 m, respectively, which are also greater than those reported in the rat kidney. Despite the comparable body weight, the total number and mean individual volume of glomeruli in the Persian squirrel kidney were greater than those in the rat kidney. Overall, the stereological variables of the kidneys elucidated in this study are exclusive to the Persian squirrel. Our findings, together with future renal physiological data, will contribute to a better understanding of the renal structure-function relationship in the Persian squirrel.