Hyaline Cartilage Structure

Study Notes

Capsular (Pericellular) matrix: a ring of densely staining matrix around the chondrocyte, containing the highest concentration of sulfated proteoglycans, hyaluronan, biglycans, and multiadhesive glycoproteins.
Territorial matrix: a region surrounding the isogenous group, containing a randomly arranged network of type II collagen fibrils with smaller quantities of type IX collagen.
Interterritorial matrix: a region surrounding the territorial matrix, occupying the space between groups of chondrocytes.

Zone of Resting Cartilage: chondrocytes are haphazard and have no definite arrangement.
Zone of Proliferating Cartilage: chondrocytes are arranged in rows, parallel to the long axis of the specimen.
Zone of Maturation and Hypertrophy: chondrocytes and lacunae enlarge to a cuboidal shape.
Zone of Calcification: matrix appears darker staining, and lacunae have opened up.
Zone of Developing Trabeculae: osteoblasts gather on the surface of cartilage plates or bone trabeculae.
Zone of Resorption: characterized by the presence of osteoclasts.

Hyaline cartilage provides a model for the developing skeleton of the fetus.
It is the precursor of bones that develop by the process of endochondral ossification.
During development, most cartilage is replaced by bone, leaving residual cartilage at growth sites (epiphyseal growth plates).
In adults, cartilage remnants are found in articular surfaces of joints, rib cage, trachea, bronchi, larynx, and nose.

Elastic cartilage is distinguished by the presence of elastin in the cartilage matrix.
It contains a dense network of branching and anastomosing elastic fibers and interconnecting sheets of elastic material.
Found in the external ear, walls of the external acoustic meatus, auditory (Eustachian) tube, and epiglottis of the larynx.
Unlike hyaline cartilage, the matrix of elastic cartilage does not calcify during aging.

Fibrocartilage is a combination of dense regular connective tissue and hyaline cartilage.
Typically present in intervertebral discs, pubic symphysis, insertion of tendons, and structures within certain joints.
The ECM of fibrocartilage contains varying amounts of both Type I and Type II collagen fibrils.
In addition, ground substance contains larger amounts of versican (a proteoglycan monomer secreted by fibroblasts) than aggrecan (produced by chondrocytes) molecules.