OSTEOGENIC SARCOMA

PART II: THE FIBRO-OSSEOUS FORMS OF OSTEOGENIC SARCOMA  Ossifying connective tissue is of two types, that which ossifies in the wake of calcified cartilage and that which forms bone of the menbranous type independently and directly. While these two forms of ossification have long been recognized by embryologists, it is erroneous to assume that the formation of membranous bone is restricted to a few flat bones of the skull and that so-called intracartilaginous ossification (bone in the wake of the cartilage) is the uniform rule in the long bones. It is true that the cancellous portion of the long bones is produced by a more primitive ossification which is dependent on a previous storage of calcium in cartilage. But it is likewise true that in the appendicular skeleton a rim of compact cortical bone is formed directly by a more highly differentiated connective tissue after the perichondrium has been transformed