Glomerular morphometry in the Munich Wistar rat: effects of sub-total renal ablation

In the development of disease of the glomerular capillary bed there is a triple association between loss of nephrons, adaptive hyperfunction of residual glomeruli, and hypertrophy and sclerosis of these glomeruli. Sclerosis is closely associated with hypertrophy, and both are closely tied to loss of nephrons. This paper quantifies the response over a period of 12 weeks of superficial cortical (SC), midcortical (MC) and juxtamedullary (JM) glomeruli of the Munich Wistar rat to the ablation of approximately 5/6 of renal tissue. The mean areas of peripheral and mesangial glomerular basement membrane (GBM) were estimated by stereologic methods. While the overall estimated area of the GBM increased in response to ablation by a factor of 2.4, the peripheral GBM area increased only by a factor of 2.15, and by way of contrast, the mesangial GBM area by a factor of 3.25. The latter difference is interpreted as a measure of glomerulosclerosis. There are no marked differences between the changes in SC, MC, or JM glomeruli. These findings are consistent with the association of glomerular hypertrophy and glomerulosclerosis, and with recent suggestions that glomerular hypertrophy and sclerosis following subtotal renal ablation are driven by local or circulating growth factors.