The extracellular matrix secreted by chondroblasts is composed of fibers, collagen, hyaluronic acid, proteoglycans, glycoproteins, water, and a host of macromolecules.

Within finished cartilage, collagen fibers compose 10-20% of the volume, water 65-80%, and the proteoglycan-hyaluronic acid aggregates the remaining portion.

Due to the proliferative nature of chondroblasts, cells compose a larger portion of the composition than what is normally found within completed cartilage.

[3] Collagen Type II fibers are responsible for giving the future cartilage matrix its tensile strength.

These chains together are attached to a hyaluronic acid backbone which, in conjunction with the collagen fibrils, create an interstitial intrafibrillar space in which water is held in by the negative charge of the proteoglycans.

[5] An important genetic component of this process is Sox9, a HMG box transcription factor, which marks progenitor cells for chondrogenic differentiation.

After Wnt14 is initiated, phosphorylation of the β-Catenin that would normally mark the protein for destruction is suppressed which allows it to accumulate and eventually go into the cell nucleus to bind to the LEF/TCF transcription factors which lead both to the destruction of any remaining phosphorylated β-Catenin as well as the differentiation of mesenchymal progenitor cells into osteoblasts.

[7] Retinoic acid, part of a family of molecules called retinoids, need to be repressed in order for Chondroblasts to form.

[8] It has also been suggested that the inhibition of receptor mediated retinoid signaling induces Sox9 expression which is considered a “master switch” for the differentiation of chondroblasts.

HMGB-1, a growth factor which promotes chondrocyte division while receptors for advanced glycation products (RAGE) mediated chemotaxis to clean up cell debris resulting from the damage.

Part of this inability to regenerate quickly from injury results from the relative avascular nature of cartilage as compared to other connective tissues of the human body.