Bone

Intramembranous bone formation. In the fetal skull, plates of bone are laid down in the mesenchymal field. This image shows woven or immature bone, which tends to be more cellular than lamellar or adult bone. Osteoprogenitor cells differentiate into osteoblasts, which produce the osteoid or uncalcified bone. Once the bone is calcified the osteocytes are trapped in the bone matrix. Osteoclasts continue to remodel the bone as necessary. UCLA Histology Collection.