Osteocyte Health Dictionary

n. the hard extremely dense connective tissue that forms the skeleton of the body. It is composed of a matrix of collagen fibres impregnated with bone salts (chiefly calcium carbonate and calcium phosphate; see hydroxyapatite), in which are embedded bone cells (see osteocyte). Compact (or cortical) bone forms the outer shell of bones; it consists of a hard virtually solid mass made up of bony tissue arranged in concentric layers (Haversian systems). Spongy (or cancellous) bone, found beneath compact bone, consists of a meshwork of bony bars (trabeculae) with many interconnecting spaces containing marrow. (See illustration overleaf.)

Individual bones may be classed as long, short, flat, or irregular. The outer layer of a bone is called the *periosteum. The medullary cavity is lined with *endosteum and contains the marrow. Bones not only form the skeleton but also act as stores for mineral salts and play an important part in the formation of blood cells.... bone

combining form denoting a cell. Examples: chondrocyte (cartilage cell); osteocyte (bone cell).... cyte

mature *bone, in which the collagen fibres are arranged parallel to each other to form multiple layers (*lamellae) with the osteocytes lying between the lamellae. It exists in two structurally different forms: cortical (compact) and cancellous (spongy) bone. See also woven bone.... lamellar bone

(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