The commonest form of inherited retarded growth. It is a dominant hereditary disorder of endochondral ossi?cation, caused by mutations of ?broblast growth factor receptor 3 genes.The long bones of the arms and legs fail to grow properly, while the trunk and head develop normally. Achondroplasia affects both sexes and, while many infants are stillborn or die soon after birth, those who survive have normal intelligence, a normal expectation of life and good health.... achondroplasia
(osteogenesis) n. the formation of *bone, which takes place in three stages by the action of special cells (osteoblasts). A meshwork of collagen fibres is deposited in connective tissue, followed by the production of a cementing polysaccharide. Finally the cement is impregnated with minute crystals of calcium salts. The osteoblasts become enclosed within the matrix as osteocytes (bone cells). In intracartilaginous (or endochondral) ossification the bone replaces cartilage. This process starts to occur soon after the end of the second month of embryonic life. Intramembranous ossification is the formation of a *membrane bone (e.g. a bone of the skull). This starts in the early embryo and is not complete at birth (see fontanelle).... ossification
(growth plate) a horizontal band of tissue located between the ends (*epiphyses) of a long bone and the growing zone (*metaphysis) of the shaft. It is composed of cartilaginous, bony, and fibrous components that combine to allow for longitudinal and latitudinal growth and remodelling of the developing bone (endochondral *ossification). See also Salter-Harris classification.
physo- combining form denoting air or gas.... physis
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