[Ultrastructural study of a chordoma].

An ultrastructural study of a case of sacral chordoma is reported. The cell type was monomorphic. The epithelial nature and the secretory function of the tumour cells was obvious in view of their content of desmosomes and the presence of mucopolysaccharide in the ergastoplasm and in the extracellular space. Because of the lack of intracytoplasmic vacuoles in the case reported, the authors doubt the individuality of the so-called "giant physaliphorous cell". The authors consider that the vacuolar appearance of the tumour cells is due to cytoplasmic invaginations caused by the enlarged extracellular space containing acid mucopolysaccharides or by processes of histiocytes containing the same material.