Osteoblasts deposit bony matrix around themselves, which form spongy bone

Masses of hyaline cartilage form models of future bones. (3rd month of prenatal dev.)

Endochondral Growth 1st

Cartilage tissue breaks down. Periosteum develops.

Endochondral Growth 2nd

Blood vessels and differentiating osteoblasts from the periosteum invade the disintegrating tissue.

Endochondral Growth 3rd

Osteoblasts form spongy bone in the space occupied by cartilage

Endochondral Growth 4th

Osteoblasts beneath the periosteum deposit compact bone.

Endochondral Growth 5th

Osteoblast become osteocytes when bony matrix completely surrounds them. Endochondral

Endochondral Growth 6th

Osteoblasts deposit bony matrix around themselves, which form spongy bone

Intramembranous Growth 1st step

Dense networks of blood vessels supply the developing spongy bone

Intramembranous Growth 2nd

Osteoblasts become osteocytes when bony matrix completely surrounds them.

Intramembranous Growth 3rd

Embryonic connective tissue on the surface of each developing structure condenses to form periosteum

Intramembranous Growth 4th

Osteoblasts on the inside of the periosteum deposit compact bone over the spongy bone.

Intramembranous Growth 5h