Morphological characteristics, especially the malignant features, of chordoma in comparison with the notochord

Twelve cases of the chordoma, including 4 cases with metastases, have been examined by light and electron microscopy for a comparison with 5 cases of the human notochord. Observed similarities in the histological and ultrastructural characteristics of the chordoma with those of the notochord suggested the histogenetic origin of the chordoma from the remnant of notochord. A "diffuse pattern" that was seen in the histological appearance of 4 cases of the chordoma, including 2 cases with metastases, was not observed in the notochord and was considered to indicate the malignant nature of such chordoma. Electron microscopy of the physaliphorous cells characteristic of the chordoma demonstrated intracytoplasmic large vacuoles containing glycogen.