Biological and morphological characteristics of a transplanted cartilaginous tumor derived from a human osteogenic sarcoma.

A cartilaginous tumor derived from a human osteogenic sarcoma of the mandible has been maintained by serial passage to nude mice. Tumor growth was multilobular. Radiopaque spots were seen scattered throughout the tumor at three months after transplantation. Both light and electron microscopic examination at three months revealed that the tumor contained cartilaginous cells at various stages of differentiation. There was metachromasia throughout tumor lobules except in the marginal region. Von Kossa staining was positive in the central region. Ultrastructural study identified four subtypes of chondrocytic cells of a neoplastic nature. In the extracellular matrix around hypertrophic cells, matrix vesicles were observed with mineral deposits. Alkaline phosphatase was found on the plasma membrane and Golgi complexes of hypertrophic cells, and on matrix vesicles. Thus cell lineage and the manner of calcification of the transplanted tumor were similar to those of epiphyseal growth cartilage.