At 12 weeks peritubular capillary ( PTC ) EC proliferation and PTC density were higher in female RK rats whereas macrovascular changes in preglomerular vessels ( smooth muscle cell proliferation , medial wall thickening , and adventitial fibrosis ) were less prominent . ^^^ In conclusion , female RK rats developed less glomerulosclerosis and renal failure compared to male RK rats in association with greater preservation of PTC and less preglomerular arteriopathy . ^^^