Distribution of serum protein labeled with Evans blue in the walls of extra- and intracranial blood vessels of the cat☆

Abstract Distribution of endogenous serum protein labeled with Evans blue within the walls of the aorta, peripheral arteries and veins and intracranial blood vessels was investigated by fluorescence microscopy in cats after perfusion fixation. Evans blue-serum protein reaction product shows a gradient distribution across the walls of the aorta and extracranial vessels and is deposited in the elastica interna of intracranial extraparenchymal arteries and arterioles. Reaction product is not evident in intracranial veins or brain parenchymal vessels except in the choroid plexi and in the elastica of lenticulo-striate arterioles. Results confirm conclusions derived by other techniques concerning distribution of serum protein in the aortic wall. A similar distribution is found in branch arteries of the aorta. Permeability of extraparenchymal intracranial arterial endothelium to serum protein appears to be a normal phenomenon in cats. The phenomenon may have important implications in vascular pathology of these vessels. Serum-protein labeling techniques may be useful in investigations of cerebral atherogenesis.