1 – Zone of calcified cartilage
The limits of this zone cannot be always easily defined in sections.
The chondrocytes in this region (highlighted in light green) constitute the end of the rows of cartilage cells of the stack of hypertrophic chondrocytes. Note that their volumes are greatly increased.
The sites previously occupied by living chondrocytes enlarged when compared to chondrocytes of the other zones.
Many chondrocytes are fragmented as a result of cell death and several places that once contained chondrocytes now appear empty.
Septa of cartilage extracellular matrix, which delimit the spaces formerly occupied by the chondrocytes, become quite thinner (highlighted in turquoise blue).
Calcium salts are progressively deposited in the matrix septa.
2 – Zone of ossification
Unlike the cartilage tissue from which this region derives, this zone is vascularized and contains many osteoblasts, other bone tissue cells, and bone marrow.
This region is highlighted in pink, and some of its details will be analyzed on the following pages.
