noun
collagen fiber
Medical term for the fibrous protein that provides structural support in connective tissues.
膠原線維は皮膚や腱に多く含まれている。
Collagen fibers are abundant in skin and tendons.
コラーゲン is the common loanword for the protein itself, while 膠原線維 specifically refers to the fibrous form in tissues.
From 膠原 (こうげん, 'collagen') + 線維 (せんい, 'fiber'). 膠原 is a kanji compound meaning 'glue-origin', referring to the gelatinous nature of collagen.