Bony Tissue. Indirect or Chondral Bone Formation. Continuation of Plate 95.

Abstract

As the periosteal bony band (Fig. A1) extends toward the epiphyses (Fig. A2), the cartilage cells within the diaphysis (Fig. A3) become larger and richer in glycogen and lipids. Although they still produce alkaline phosphatase, sulfated proteoglycans, and matrix vesicles, the cartilage matrix is reduced and soon becomes calcified. This calcification and the periosteal bony band cause the nutritive processes to become completely interrupted in the diaphysis. Thus, the hypertrophied cartilage cells die. Such an area in the hyaline cartilage visible to the naked eye is termed a primary ossification center.