[Morphogenesis of the intimal thickening observed in nonspecific aortoarteritis]

Thickening of blood vessel segment intima (aorta, carotid, femoral and renal arteries) excised from 9 patients during surgery for nonspecific aortoarteritis was studied, using electron microscopic autoradiography. A large number of vessels of capillary and precapillary type were found among cells and in the intracellular substance of thickened intima. Vascular endotheliocytes and pericytes were easily labelled with 3H-uridine. It is suggested that cells appear in the thickened intima due to growth of small vessels of the capillary type, covered with pericytes which turn into fibroblast-like cells producing intracellular substance, and not due to smooth muscle cell migration from the media. In addition, it was found that the lumens of some vessels were filled with fibrillar material and that the cells underlying the vessel stayed apart, not forming a continuous circle. It is suggested that the damage of normal vascular structure can also result in the appearance of free cells.