GLOMERULAR NUMBER AND CAPILLARY DIMENSIONS IN THE NORMAL LAMB KIDNEY

Reduced nephron endowment, either inherited or acquired, has been linked to adult renal pathology as well as hypertension. The sheep provides an excellent model for studying nephrogenesis and renal development because, as in humans, nephrogenesis is complete before birth. In the present study, the physical disector/fractionator method was used to estimate the total number of glomeruli, and thereby nephrons, in normal lambs. Glomerular capillary parameters including mean capillary length per glomerulus, mean capillary surface area per glomerulus and total renal filtration surface area (TRFSA) were also estimated. Total glomerular, and hence nephron number was 333,832 ± 69,560 (mean± standard deviation). TRFSA was 10.95 ± 3.64 x 104 mm2• These results establish a methodology for future investigations, using the sheep as a model, into the effects of depleted nephrogenesis on renal pathology in later life.