Type III Collagen
A collagen type found in skin, blood vessels, and internal organs that provides structural support and elasticity. Type III collagen is prominent in early wound healing and is gradually replaced by type I collagen during tissue maturation and remodelling.
Technical Context
Type III collagen is a homotrimer of three alpha-1(III) chains that forms fine reticular fibres. It is particularly abundant in: embryonic/foetal skin, blood vessel walls (tunica intima and media), intestinal wall, uterus, and early wound healing tissue (granulation tissue contains predominantly type III collagen before remodelling). During wound maturation, type III collagen is gradually replaced by type I collagen — this transition increases tissue tensile strength from approximately 20% of normal at 3 weeks to 70-80% of normal by 12 months (mature scars never fully recover original strength). The type III/type I collagen ratio is a marker of wound maturity and scar quality — higher type III proportion indicates immature or poorly remodelled tissue. Mutations in COL3A1 (type III collagen gene) cause Ehlers-Danlos syndrome vascular type, characterised by fragile blood vessels and organs.