Morphometric analysis of normal glomerular epithelial cells in rat and human

It has been postulated that morphological changes of podocytes might be related to glomerular sclerotic lesions in experimental models and patients with glomerular diseases. To estimate the absolute number of podocytes in mammalian normal glomerulus, we analyzed normal glomeruli in four rats and six humans. In PAS stained light microscopic sections, at least 25 midsections of open glomeruli were photographed. Stereologic estimation was performed to obtain the following values: absolute values of glomerular volume (V), glomerular surface area (S), podocyte and intraglomerular cell number per glomerulus (P and IGC), glomerular surface area covered by one podocyte (S/P) and glomerular volume occupied by one intraglomerular cell (V/IGC). The glomerular volume, glomerular surface area and podocyte and intraglomerular cell numbers per glomerulus of human were significantly increased compared with those of the rat (V: 2.70 +/- 0.86 > 0.89 +/- 0.19, S: 4.84 +/- 1.26 > 1.88 +/- 0.26, P: 407.7 +/- 88.2 > 153.8 +/- 84.0, p < 0.01 vs rat). On the other hand, there were no significant differences in glomerular surface area covered by one podocyte and glomerular volume occupied by one intraglomerular cell between the humans and rats (S/P: 1.25 +/- 0.20, 1.29 +/- 0.05, V/IGC: 2,471 +/- 487, 2,227 +/- 201, p < 0.01 vs rat). These data were almost the same as previously reported values. It appears that these values can be considered as standards for rats and humans in morphometric analysis of the glomerulus.