This addition to the surface is called appositional growth. See PJH for adult bone structure. E.g. PJH Fig. Since in modern vertebrates only warm blooded adults form Haversian systems, their presence in the fossil has been used to argue that dinosaurs were warm blooded. Slides 21 and 23-27 are from the same preparation.
Cartilage always arises from mesenchymal condensations.
This tissue is very uniform in appearance because cartilage contains only chondrocytes and cartilage matrix. No blood vessels or nerves are present in cartilage. Cartilage cells, chondrocytes, can divide within their lacunae and this produces cartilage that can grow because the matrix is nonmineralized and deformable. This is called interstitial growth. Low magnification to show the epiphysis, epiphyseal plate, and diaphysis.