FIG 4:

Photomicrographs of a glomerulus and an intralobular artery from a dog with CRGV, stained with haematoxylin and eosin [H&E] (a and c) and Masson's trichrome (b and d). There is fibrinoid vascular necrosis (asterisks) of intralobular arteries and arterioles. Glomerular capillaries are severely distended and contain red blood cells, many of which are fragmented. Distension of glomerular capillaries is due to dissolution of the mesangial matrix (mesangiolysis). Tubules are undergoing degeneration and necrosis; most tubules contain protein casts whereas some contain red blood cell casts.