1.6 Interstitial Growth

Width

increases via appositional growth along bone collar

Resorbtion

when osteoclasts release Ca into blood

Remodeling

when osteoclasts take up Ca from blood and incorporate it into bone

Interstitial growth

bone lengthening; occurs within epiphyseal plate; 5 zones; the first being most near the epiphysis and last being most far away (towards diaphysis)

Osteopropgenitor

cells that develop into osteoblasts

Epiphyseal plate

hyaline cartilage at the boundary of the epiphysis and diaphysis; site of interstitial growth of cartilage

Arterial supply

important because it supplies blood vessels that penetrate periosteum, osteoblasts enter via periosteal bud, blood brings osteogenic cells and CaPO4

Length

increases via interstitial growt of cartilage that is ossified

Osteoclasts

very large cell that is active during bone remodeling; turn woven bone into lamellar bone, responsible for remodeling and resorbtion

Ossification

zone interstitial growth where walls that were calcified between lacunae break down, forming longitudinal channels for capillaries to invade, now considered bone

Resting

zone of cartilage in interstitial growth that has not yet begun to divide; nearest to epiphyseal plate, composed of small chondrocytes, secures epiphysis to epiphyseal plate

Hypertrophic

zone of cartilage in interstitial growth that is characterized by large, dying chondrocytes whose matrix is all that remains of the cell; chondrocytes cease dividing and begin to hypertrophy, resorbing the cartilage matrix; lacunae become thin

Calcified

zone of cartilage in interstitial growth that is only a few cells thick, minerals are deposited in matrix between lacunae columns; calcification kills chondrocytes; matrix is opaque, not yet bone

Proliferating

zone of cartilage in interstitial growth; staking, chondrocytes are undergoing rapid mitotic cell division enlargement and become aligned like a stack of coins into columns of flattened lacunae