Bone Growth: Growth in Height Occurs at the Growth Plate

The disc of hyaline cartilage that is interposed between the epiphysis and the metaphysis of each of the long bones, is responsible for its elongation and thus, when the lower limbs are concerned, for increases in bodily height. This so-called growth plate is avascular, aneural and alymphatic. It consists solely of chondrocytes and an extracellular matrix which the cells elaborate. The growth plate is architectonically striking in so far as the chondrocytes are aligned in strictly vertical columns, which represent the functional units of longitudinal bone growth. The growth process begins with the slow division of chondrocytes in the superficial 'stem-cell' zone, and proceeds with their rapid proliferation in the adjacent zone. These cells then undergo a process of progressive enlargement, which culminates in the zone of terminal hypertrophy.

The life-history of any given cell is recapitulated in a vertical column. The neoformation of cartilage in the axial direction is synchronized with its destruction at the vascular invasion front of the metaphysis and results in an elongation of the bony trabeculae. The mechanism that governs the highly co-ordinated sequence of events that underlies the growth of the long bones is complex; it is subject to influence by genetic, hormonal, nutritional, environmental and pathological factors.