Bone: endochondral ossification
A longitudinal section through a fetal finger shows progressive changes that occur in long bones. Hyaline cartilage forms a template for the future bone and is gradually replaced by bone. Because bone is replacing a cartilage model, this ossification is called endochondral ossification. 4x
Cartilage >
Typical hyaline cartilage formed the original template of these long bones and still exists in the region of the future epiphyses.
Periosteal band >
Early in endochondral ossification, the perichondrium becomes vascularized, enabling this layer to act as a periosteum, depositing bone at the periphery of the cartilage template. This periosteal band is formed by intramembranous ossification, as bone is laid on, rather than replacing, cartilage. The periosteal band supports the forming bone and contributes to its future diaphysis.
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Image source >
This image was taken of a slide from the University of Mississippi collection.
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