Sex differences in kidney morphology and glomerular filtration rate in mice.

The relative kidney weight (1.44% greater than 1.15% greater than 1.07%) and the GFR (44 greater than 39 greater than 35 ml/min . m2) are higher in adult males than in adult females or in orchiectomized males. In contrast, GFR based on kidney weight is smallest in healthy males (1.02 less than 1.22; 1.22 ml/min . g). Only the cortex tissue seems to be increased in males, because its width (1.67 mm) is greater than in females (1.26 mm), while medullary width is identical (2.4 mm) in both sexes. Enlargement of the cortex in males can be accounted for by the nonglomerular tissue, because glomerular diameters (120 micrometers) do not differ and the number of glomeruli in representative sections is lower than in females. Cuboidal cell transformation of the outer layer of Bowman's capsule was observed in 60% of the glomeruli of the males and in 5% of the females. It might be an indicator for hyperplasie of the proximal tubular cells in the males.