Table 2. The collagen subtypes of cartilage.

E, Elastic; F, fibrocartilage; H, hyaline; ECM, extracellular matrix; PCM, pericellular matrix; TM, territorial matrix. Refer to the subsections under ‘Collagen subtypes in cartilage’ for information about the isoforms.

Collagen subtype	Cartilage location	Description	Structure	Refs
I	ECM (E,F)	Main fibrillar type of fibrocartilage and elastic cartilages	T3 1	111, 114,121
II	ECM (E,F,H)	Main fibrillar type of hyaline, fibrocartilage, and elastic cartilages	T3 1	3, 111,112
III	ECM (E,F,H)	Fibrillar type co-assembling with collagen type I Involved in repair response with collagen type II	T3 1	124,179,180
IV	PCM (H)	Tetrameric network in PCM of articular cartilage Potential involvement in chondrocyte homeostasis	T3 2	201-204
V	ECM (E,F)	Fibrillar type co-assembling with collagen type I	T3 3	181-183
VI	PCM (E,F,H)	Regulation of PCM properties and mechanotransduction	T3 4	205-207
IX	ECM (E,F,H)	Forms crosslinks with collagen type II Forms collagen type II-IX-XI heterofibrils	T3 5	184,185
X	Deep zone (H)	Produced by hypertrophic chondrocytes Marker of endochondral ossification	T3 6	62,208
XI	ECM (E,F,H)	Involved with fibrillogenesis of collagen type II Forms collagen type II-IX-XI heterofibrils	T3 7	157,189
XII	ECM (E,F,H)	Codistributed with collagen types I and II May contribute to fibril alignment and stabilization	T3 8	192-194
XIII	Deep zone (H)	Involved with endochondral ossification	T3 9	210,211
XIV	ECM (E,F,H)	Involved in fibrillogenesis of collagen types I and II	T3 8	196,197
XVI	TM (H)	Associates with collagen type II fibrils May stabilize larger collagen fibrils	T3 10	198-200
XXII	Synovial junction (H)	Associates with collagen type VI Role in cartilage understudied	Not yet determined	212, 213
XXVII	Deep zone (H)	Associated with endochondral ossification Structural role in PCM of growth plate cartilage	Not yet determined	215-217