Phagocytosis of mast cell granules by fibroblasts of the human gingiva.

Mast cell granules have been detected ultrastructurally within the cytoplasm of fibroblasts in fibrous hyperplastic lesion of the human gingiva. This finding is interpreted as phagocytosis of mast cell granules by fibroblasts. It is estimated that phagocytosis of mast cell granules occurred in four to six per cent of the fibroblasts. The result of present study suggests that mast cells play some role in fibroblast activity not only in animals as reported previously, but also in human connective tissue.