Electron Microscopic Studies of Collateral Arteries:An Experimental Investigation in the Rabbit after Occlusion of the Femoral Artery

Abstract

The ultrastructural changes undergone by collateral arteries during their development were studied in the rabbit after occlusion of the femoral artery. Profound alterations in shape and composition of cytoplasmic components were noted in the endothelial and smooth muscle cells. Signs of high metabolic effort and increased protein synthesis were found in these cells throughout the period of investigation. Early in the development, modified smooth muscle cells made their appearance in the intima, and their possible function is discussed. In the endothelial and smooth muscle cells, as well as in the extracellular space, vacuole-like formations, presumably representing water-containing inclusions expelled from adjacent cells, were noted. In late stages of collateral development there were signs of focal cytoplasmic degeneration in endothelial and smooth muscle cells. Increased pressure and/or flow appear to be responsible for the ultrastructural changes noted in this study. These changes are not specific for collateral arteries, however, but presumably reflect a common reaction of arteries to injury.