Juvenile ossifying fibroma: an ultrastructural study.

The ultrastructural features of a juvenile ossifying fibroma of the maxilla are described. The stromal portion of the tumor was composed of osteoblasts and to a lesser extent of fibroblasts. The bone spicules were rimmed by osteoblasts and osteoclasts. Calcification was seen to occur along the collagen fiber matrix, corresponding to calcification of osteoid, and also in the form of intracellular and extracellular crystallization. The latter form of calcification corresponded to so-called psammoma-like bodies, and was considered characteristic of this subtype of ossifying fibroma.