Cartilage and bone formation in arterial wall. 1. Morphological and histochemical aspects.

Cartilaginous and/or osseous foci were observed in eight aortas from 20 rabbits immunized against heterologous aorta homogenates and sacrificed 11 to 24 months later. They were studied by means of histological and histochemical methods and compared with normal aortas, cartilage and bone. Some of the observed changes seemed to be true markers of these transformations. Chondroid metaplasia was characterized by 1) generalized increase in alcianophilic hyaluronidase sensitive substances. 2) Appearance of Dermatan and/or Keratan sulfates round some isolated cells. 3) Advent of G6 Pase and Alk. Phase activities in cells adjacent to osseous foci. Osteous metaplasia was characterized by 1) decrease, then disappearance of alcianophilic and PAS positive material, 2) increase in osteoblastic alkaline Pase-activities.