Collagenous

Collagenous is an adjective relating to collagen, a major structural protein of the extracellular matrix in animals. The term derives from collagen, combined with the suffix -ous, meaning possessing or characterized by.

In biology and medicine, collagenous describes tissues or deposits that contain substantial amounts of collagen or thick collagen fibers. In histology, collagenous tissue refers to dense connective tissue such as tendons, ligaments, dermis, and the stroma of various organs, where collagen fibers confer tensile strength and structural support. Collagenous bands or sheets may also be described in histological sections as collagen-rich.

In pathology, the descriptor appears in specific conditions. A well-known example is collagenous colitis, a form of microscopic colitis characterized by a thick subepithelial collagen band in the colonic mucosa, typically with inflammatory cells in the lamina propria. Clinically, it presents with chronic, nonbloody watery diarrhea; diagnosis relies on colon biopsy and histological criteria, and management often involves dietary measures, stopping suspected drugs, and medications such as budesonide.

The term is also used more generally to denote tissues in which collagen is the dominant extracellular component, distinguishing them from tissues rich in elastin, reticulin, or other extracellular proteins. While "collagenous" indicates composition, it does not specify a disease by itself.