Key points are not available for this paper at this time.
In recent years a number of papers have appeared tending to show that the formation of bone in arteries is not as rare as has been generally supposed. In the large vessels in six cases of arterio-sclerosis, MSnckeberg was able to find sixteen osseous foci. The older literature seems to indicate that the aorta and heart valves are the favorite sites for ossifying processes in the cardio-vascular system. M6nckeberg's contribution, however, has clearly demonstrated that not only the aorta, but also vessels of the extremities, such as the femoral, the anterior and posterior tibial arteries may not infrequently be involved. While engaged in a study of the pathology of vessels in gangrene of the lower extremities, we encountered rather extensive areas of ossification in the arteries of two limbs, both obtained from patients afflicted with advanced arteriosclerosis. We wish to record the histological features presented by one of the cases, to point out how these differ from what has been observed by other authors and to discuss in brief the theories that have been advanced in explanation of heteroplastic bone formation. Our ease was particularly interesting because of the large number of bony plaques and because so many of the larger arteries of the extremity were affected. Either true bone or osteoid tissue was found distributed throughout their length in the following arteries: the anterior and posterior tibial, the peroneal, and the plantar; in short, in all of the five vessels examined except the dorsalis pedis. 1 A perusal of the literature failed to reveal any record of bone for-* Received for publication :February I8, I9o8. 1We are unable to state the extent of the areas of ossification because we made no serial sections; but in one instance, as was seen in longitudinal section, the osteoid patch extended the entire length of the piece, namely, 3 ram. 354
Buerger et al. (1908) studied this question.