Ossification, endochondral

VanWesenbeeck, L., Odgren, P.R., MacKay, C.A., D Angelo, M., Safadi, F.F., Popoff, S.N., VanHul, W., and Marks, S.C. Jr (2002) The Osteopetrotic Mntation Toothless (tl) is a Loss-of-Function Frameshift Mutation in the Rat Csfl Gene Evidence for Crucial Role for CSF-1 in Osteoclastogenesis and Endochondral Ossification. Proceedings of the National Academy of Sciences of the f/5A99, 14303-14308. 

Rabie ABM, Tang GH and Hagg U (2004) Cbfal couples chondrocytes maturation and endochondral ossification in rat mandibular condylar cartilage. Arch. Oral Biol. 49 109-118. 

Tang GH and Rabie ABM (2005) Runx2 Regulates Endochondral Ossification in Condyle during Mandibular Advancement. J. Dent. Res. 84 166-171. 

Yasui N, Ono K, Konomi H and Nagai Y (1984) Transitions in collagen types during endochondral ossification in human growth cartilage. Clin. Orthop. Relat. Res. 183 215-218. 

Inhibitors of matrix metaloproteases also reside in normal hyaline cartilage, where they may inhibit vascular invasion [107]. Blood vessel invasion into cartilage induces endochondral ossification, a normal process in the growth of long bones, but which would be undesirable, for example, in the articular cartilage. Loss of angioinhibitory activity within articular cartilage may contribute to the vascular invasion and ossification, which characterizes the osteoarthritic joint [108, 109],... 

Ossification is the process of the synthesis of bone from cartilage. There are two types of ossification—in-tramembranous and endochondral ossification. Bone may be synthesized by intramembranous ossification, endochondral ossification, or a combination of the two. 

Endochondral ossification is the gradual replacement of cartilage by bone during development. This process is responsible for formation of most of the skeleton of vertebrate animals. In this process, actively dividing bone-forming cells (osteoblasts) arise in regions of cartilage called ossification centers. The osteoblasts then develop into osteocytes, which are mature bone cells embedded in the calcified (hardened) part of the bone known as the matrix. 

Most bones arise from a combination of intramembranous and endochondral ossification. In this process, mesenchyme cells develop into chondroblasts and increase in number by cell division. Then, the chrondrob-lasts enlarge and excrete a matrix which hardens due to... 

Figure 12 Skeleton of a day 20 control rat fetus. The ossification in the skull, vertebrae, ribs, and sternebrae is nearly complete. Endochondral ossification of the pectoral and pelvic girdle and limbs is progressing x 3.2).

The growth plate chondrocytes undergo proliferation, growth, degradation, mineralization, and resorption and provide the support structure for new bone formation. Bones can increase in length and width through this process. Endochondral ossification occurs near the base of the articular cartilage at the joints. 

Nucleation of calcium phosphate precipitation within the matrix vesicles is mediated by phosphatidylserine, which comprises about 8% of the phospholipids of the inner cytosolic membrane surface (Fig. 9.5a). Calbindin in the vesicle (Fig. 9.5b) may also contribute. Rapid mineral growth within the vesicle keeps the concentration of dissolved calcium and inorganic phosphate ions so low that additional Ca2+ and Pi ions spontaneously enter from the extracellular fluid via their respective transporters. Attached type II and type X collagens from cartilage in the growth plate enhance calcium ion transport and calcification during endochondral ossification (Fig. 9.5b). 

Bone formation may involve either endochondral ossification as in most long bones, or membranous ossification as in the calvaria and the dentaries. The Prxl defects were seen in both types of bones and the affected bones were also diverse in their embryonic origin, as they included facial bones that are derived from neural crest, limb bones that originate from lateral plate mesoderm, and vertebrae that originate from paraxial (somitic) mesoderm. 

Fig. 1. A photomicrograph in the rostral portion of a nine-week old fetal mandible, showing the mesenchymal tissue in the midline (m), bounded by labial bony trabeculae (It). Notice the closeness of the bilateral portions of Meckel s cartilage (me). Oral bony trabeculae could be identified (ot). th = tooth premordium p = lip arrow = endochondral ossification in...

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