Costal hyaline cartilage

(hematoxylin and eosin)

The perichondrium is an external coat of the cartilage. It consists of two layers:

• outer layer is represented by connective tissue proper with minor blood vessels #1, #2,
• inner (chondrogenic) layer, which contains mainly poorly differentiated cells (prechondroblasts and chondroblasts);

The cartilage comprises the following cell types:

• beneath the perichondrium, intercellular substance lacunae contain chondroblasts, which are juvenile cartilaginous cells of a fusiform shape. They are parallel to the cartilage surface;
• there are also chondrocytes that are found deeper in lacunae; these are mature cartilaginous cells of elliptical or rounded shape. They may be solitary or form isogenous groups #1, #2 (up to 8-12 cells).

The intercellular substance (matrix) comprises collagen fibers and an amorphous component, though in conventional microscopy they look like a homogenous structure because of the same refraction properties. The intercellular substance is classified into:

• territorial cell matrix #1, #2 surrounds cartilaginous cells or isogenous groups as an area with blurred edges. It is highly basophilic due to an elevated glycosaminoglycan content;
• interterritorial matrix corresponds to previously formed intercellular substance portions. It is slightly basophilic or oxyphilic.