Bone cells

Osteocytes

Mature bone cells that maintain the bone matrix
– Are between layers (lamellae) of matrix
– Connect by cytoplasmic extensions through
canaliculi in lamellae

Functions osteocytes

To maintain protein and mineral content of matrix
2. To help repair damaged bone

Osteoblasts

Immature bone cells that secrete matrix
compounds (osteogenesis)
– Osteoid — matrix produced by osteoblasts,
but not yet calcified to form bone
– Osteoblasts surrounded by bone become
osteocytes

Osteoprogenitor Cells

Mesenchymal stem cells that divide to
produce osteoblasts
– Located in endosteum, the inner cellular layer
of periosteum
– Assist in fracture repair

Osteoclasts

Secrete acids and protein-digesting enzymes
– Giant, multinucleate cells
– Dissolve bone matrix and release stored
minerals (osteolysis)
– Derived from stem cells that produce
macrophages