Ecchordosis physaliphora. An electron microscopic study.

I/ Ecchordosis physaliphora, an asymptomatic gelatinous excrescence arising from the clivus, is occasionally encountered at autopsy. Morphologically, ecchordosis closely resembles notochord and chordoma. All three consist of vacuolated cells that contain acid mucopolysaccharides. Under the electron microscope, the intracellular vacuoles have a smooth limiting membrane whereas the extracellular vacuoles are lined by microvilli and pinocytotic vesicles. No ultrastructural features accounting for the biological difference between ecchordosis and chordoma are observed in this study.