GENERAL HISTOLOGY

Detailed explanation-1: -Bones at the base of the skull and long bones form via endochondral ossification. In a long bone, for example, at about 6 to 8 weeks after conception, some of the mesenchymal cells differentiate into chondroblasts (cartilage cells) that form the hyaline cartilaginous skeletal precursor of the bones (Figure 6.4. 2a).

Detailed explanation-2: -Endochondral ossification involves the formation of cartilage tissue from aggregated mesenchymal cells, and the subsequent replacement of cartilage tissue by bone (Horton 1990).

Detailed explanation-3: -Chondroblasts, located in the perichondrium, are cells that play an important role in the development of cartilage. By producing extracellular matrix, chondroblasts create the main component that provides structure and strength to cartilage.

Detailed explanation-4: -During endochondral ossification, chondrocytes proliferate, undergo hypertrophy and die; the cartilage extracellular matrix they construct is then invaded by blood vessels, osteoclasts, bone marrow cells and osteoblasts, the last of which deposit bone on remnants of cartilage matrix.