Phagocytosis of collagen by fibroblasts incident to experimental tooth movement.

The upper molars of adult Wistar rats were moved lingually by a wire spring for 5 and 9 days. Collagen-containing fibroblasts in the pressure zone caused by the tooth movement were investigated morphologically (forms characterized by type A and type B compartments) and cytochemically (location of acid and alkaline phosphatase activity). The following results were obtained: The distribution of collagen-containing fibroblasts with type A or type B compartments could not be distinguished clearly in either 5-day or 9-day specimens; Acid phosphatase activity was recognized in the Golgi apparatus, lysosomes, and elliptical bodies associated with type B compartments; Alkaline phosphatase activity was positive in the plasma membrane of collagen-containing profiles and in both intracellular and extracellular collagen fibrils. These results suggest that fibroblasts are capable of phagocytosing collagen fibrils in all areas of the cytoplasmic membrane and that digestion of collagen fibrils in fibroblasts may be associated with acid and alkaline phosphatase.