The Biology of Arteriosclerosis

The experimental approach to the study of arteriosclerosis has yielded disappointing results in comparison to the vast effort expended upon the problem. Any new method of attack excites interest, and it is the special virtue of this monograph to have placed in evidence, with great clarity and a profusion of beautiful illustrations, the existence of a rich intramural vascular plexus, which has almost completely escaped the recognition of experienced pathologists. The methods used are not new ones-injection of India ink under pressure , followed by clearing with glycerine or by the Spalteholz method-but so far as the reviewer is aware, these well-tried technics have not hitherto been applied to a study of the vascular supply of normal or diseased blood vessel walls. They bring out, with startling definition, the presence of rami-fying blood vessels derived from three sources-the nutrient vessels of the adventitia, the main trunks of arterial branches close to their point of exit in their passage through the arterial wall, and small vessels arising directly from the lumen of the parent vessel. It is possible at times to distinguish arterial and venous branches, and to demonstrate the anastomoses of the latter with the venous channels of the adventitia. While it was found difficult to demonstrate this vascular network in the normal systemic arteries of man, the pulmonary aorta and the vena cava were very successfully injected; and in large animals, particularly the cow, excellent preparations were obtained. In general, the richest vascular plexuses were found in the vicinity of arteriosclerotic plaques, and it was this correlation which led the authors to ascribe an important role to the nutrient vessels in the genesis of the arteriosclerotic lesion. They discard the idea of a degen-erative process as a vague and outmoded conception which has retarded the progress of our knowledge; and they ascribe the pathogenesis of the lesions to exudation and subsequent organization of material derived primarily from the blood vessels of the arterial wall. They emphasize particularly the frequent occurrence of hemorrhages, amorphous products of blood destruction, and pigment, and even credit the extravasated blood with being the main source of the atheromatous material. Furthermore, they describe the occurrence of thrombi and of calcific deposits analogous to phleboliths within the lumina of these intramural vessels. The problem of arteriosclerosis therefore resolves itself, not into the causes of senescence or of tissue "degeneration," but into an inquiry into the specific …