Chondrogenesis in peripheral fibromas of the gingiva. Histochemical demonstration of oxytalan fibers and mucopolysaccharides.

Five lesions were studied to elucidate the histogenesis of cartilage in peripheral fibromas. Cytological features suggested direct transformation from fibroblast-like cells to chondrocytes (cartilaginous metaplasia). Supportive evidence for such differentiation was the presence of neutral and acid mucopolysaccharides in the loose stroma of the lesions as well as in the ground substance of the cartilaginous centers. In one instance, the metaplastic cartilage showed bone formation. An increased number of oxytalan fibers could be demonstrated in the fibroma and in the cartilage.