The function of bone marrow in the incorporation of a bone graft.

Transplants of bone marrow into the anterior chamber of the eye were observed by Pfeiffer to produce migration, regression, and degeneration of myelogenous and hematopoietic cells at the same time that reticular cells proliferate and differentiate into bone. This key observation raised the question of whether the bone formation is the result of proliferation and osteogenetic activity of the reticular cells, or whether mesenchymal-type cells of the host are also induced by the transplant to differentiate into bone. From a comparison of bone marrow with epiphyseal cartilage, fracture callus, cancellous bone, muscle, and other tissues. Urist and McLean suggested that in the anterior chamber of the eye, one or another, or both, mechanisms are operative. Urist demonstrated that new bone formation occurs in postfetal life by the mechanism of induction alone in an implant of demineralized bone matrix in a muscle pouch. In recent years, the inductive agent and inductive response have been under intensive investigation with the aid of new and improved biochemic concepts and methods (Lindholm and Urist).