Osteoblasts are cells with a single nucleus that synthesize bone. However, in the process of bone formation, osteoblasts function in groups of connected cells. Individual cells cannot make bone. A group of organized osteoblasts together with the bone made by a unit of cells is usually called the osteon.
Osteoblasts (purple) rimming a bony spicule (pink - on diagonal of image). In this routinely fixed and decalcified (bone mineral removed) tissue, the osteoblasts have retracted and are separated from each other and from their underlying matrix. In living bone, the cells are linked by tight junctions and gap junctions, and integrated with underlying osteocytes and matrix H&E stain.
Major features of the bone-forming complex, the osteon, composed of osteoblasts and osteocytes.
Osteoblast (Wright Giemsa stain, 100x)
Light micrograph of decalcified cancellous bone displaying osteoblasts actively synthesizing osteoid, containing two osteocytes.
Ossification in bone remodeling is the process of laying down new bone material by cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes resulting in the formation of normal, healthy bone tissue: Intramembranous ossification is the direct laying down of bone into the primitive connective tissue (mesenchyme), while endochondral ossification involves cartilage as a precursor.
Diagram showing stages of endochondral ossification
Microscopic image of the growth plate
