Abstract
Observations on the type and distribution of the acid mucopolysaccharides in grossly normal aortas, coronary arteries and basilar arteries of 130 individuals ranging from fetuses to 70 years of age utilizing new histochemical and histological methods, are summarized in Table One. Hyaluronic acid is present in the intima of the aortas of individuals ranging from fetuses to 6 years of age, in a variable number of intimas of the coronary arteries without regard to age, and in an occasional intima in the aorta of adults. Hyaluronic acid is also present in medias of the aortas (decreasing with age) and in a variable number of medias of the coronary arteries without regard to age. Hyaluronic acid is absent, irrespective of age, in the area of the internal elastic membrane of all arteries studied and in all layers of the basilar artery. It has been suggested that hyaluronic acid may play a role in nutrient transport.
The major component of the intimal acid mucopolysaccharides in fetuses, infants and young juveniles is chondroitin sulfate A and/or C. This acid mucopolysaccharide is chiefly associated with the fibrous elements. There is an increase in chondroitin sulfate B with a variable decrease in chondroitin sulfate A and/or C with aging, from older juveniles to adults.
The acid mucopolysaccharides in the area of the internal elastic membrane in fetuses, infants and juveniles is essentially chondroitin sulfate A and/or C, and is either associated with fine collagen fibers or with the absence of collagen. The ratio of chondroitin sulfate B to chonodroitin sulfate A and/or C increased with age and with severity of fragmentation and reduplication of the internal elastic membrane. There is a concomitant increase in the ratio of coarse collagen to fine collagen. The close association of chondroitin sulfate B with coarse collagen and elastic changes suggested a reinforcement mechanism to strengthen the artery wall. The presence of collagen in these areas was verified by the use of a highly purified collagenase preparation. It is suggested that chondroitin sulphate B may act as a cross-linking agent to form coarse collagen.
The intimate association between the acid mucopolysaccharides and collagen in the remainder of the media is similar to the relationship in the proximal media and area of the internal elastic membrane.
Heparitin sulfate and/or heparin is present in variable amount in the intima of all arteries, regardless of age. The clearing activity of such acid mucopolysaccharides suggests that they may play a role in release of lipids from lipoproteins in their passage through the intima.
After completion of this manuscript a study of the acid mucopolysaccharides of human aortas by chemical extraction was published by Kaplan and Meyer (38) who reported that there is an increase in chondroitin sulfate B with aging and increasing degree of atherosclerosis and the reverse for hyaluronate and chondroitin sulphate C. There was no correlation of total acid mucopolysaccharides with age. These findings seem to substantiate our histochemical findings that the ratio of chondroitin sulfate B to chondroitin sulfate A and/or C increases with age and severity of fragmentation and reduplication of the internal elastic membrane.