VARIAZIONE MORFOLOGICA E STRUTTURALE LUNGO IL DECORSO DELLA PARETE AORTICA UMANA E DI RATTO, CON PARTICOLARE RIFERIMENTO ALLA COMPONENTE PROTEOGLICANICA ALTAMENTE SOLFORATA DELLA MATRICE EXTRACELLULARE

AIMS: We sought to determine the changes in content and organization of non-collagenic constituents of the extracellular matrix (EC), focusing in particular on highly sulphated proteoglycans (HSPGs) throughout the normal human. METHODS. Histochemical staining with Alcian Blue pH 0.2 allowed for tinctorial distinction of HSPGs on complete 1-cm transverse rings removed from the ascending and descending thoracic aorta and abdominal supraceliac, suprarenal, and infrarenal aorta of young subjects at autopsy. The same protocol has been applied to Sprague-Dawley rats’ aorta to confirm the human findings. Counterstaining with Orcein and Sirius Red allowed comparing with the total content of elastin and collagen. RESULTS. Collagen/elastin ratio increases from the proximal to distal aorta. There is a significant decrease in elastin between the supradiaphragmatic and the abdominal aorta. The proportion of HSPGs does not change significantly throughout the thoracic and thoraco-abdominal aorta, while a significant increase in total HSPGs content is observed at the infrarenal site. The same findings were confirmed on rat’s tissues. CONCLUSION. The infrarenal aorta differs histologically and biochemically from the remainder of the aorta. Highly sulphated proteoglycans in the distal aorta bear an increased load as compared to the proximal aorta. A decrease in infrarenal elastin without a corresponding decrease in collagen may effect the compliance and integrity of the distal aorta. These anatomic differences may be important in predisposing the infrarenal aorta to atherosclerosis and aneurysm formation. Rats represent a feasible model to investigate the normal asset of EC constituents of the aorta.