Assertion: periosteum's osteoblast | /r/CapableOf | invade calcified cartilage template
Facets:
Source sentences:
text: Blood vessels and osteoblasts from the periosteum invade the calcified cartilage template; internally, these osteoblasts form spongy bone at primary ossification centers (and later secondary ossification centers); externally, the periosteal osteoblasts form compact bone.