[Histochemical and histoenzymatic study of experimental endarteritis in rabbits. II. Aortic endarteritis].

The placement of a polyethylene cuff around the abdominal aorta of 20 male rabbits 2,5 to 3 months old induce an adventitial reaction characterized by edema (7th day), fibroblastic proliferation (7th - 15th day), fibrosis and sclerosis (2nd - 3rd month), changes in the media including cytoenzymatic activation (1st - 3rd week), signs of hypoxia, degenerative and productive processes leading to intimal tickening. Histoenzymatic characteristics of the intimal thickening cells look like activities of smooth muscle cells, while the activities of some cellular areas recalled those of endothelial cells (high aerobic oxydoreductases and ATP/ase activities). This histoenzymatic duality is perhaps related to the histogenetic filiation of the intimal thickening cells. Histochemical data (metachromasia, alcianophilia, APS +) suggest that these cells are able to synthesize different elements of the extracellular matrix. All these features resemble femoral endarteritis obtained by the same process; moreover, in aorta the endarteritis evolves more slowly, the cellular proliferation is later and focused, the signs of hypoxia and necrosis and more pronounced. These differences are probably related to structural and metabolic dissimilarities of the two vessels, and to differences in their cellular reactivity.