Phagocytosis of collagen by human gingival fibroblasts in vitro.

Human gingival fibroblasts cultivated on collagen-coated cover slips had collagen fibrils in deep folds of the cell membranes after one hour and fully interiorized fibrils by 24 hours. In 5-day sections, fibrils were within dense bodies, some containing multiple dense granules (40 to 50 nm) aligned along the surface of the interiorized collagen fibrils.