The ultrastructure of oesophageal carcinomas: multidirectional differentiation. A transmission electron microscopic study of 43 cases.

Forty-three oesophageal carcinomas, comprising 15 squamous cell carcinomas, 22 adenocarcinomas, 5 small cell carcinomas, and 1 adenosquamous carcinoma, were examined by transmission electron microscopy. The ultrastructural features of each tumour type are detailed. Multi-directional differentiation (heterogeneity) was observed in 11 cases: 5 squamous cell carcinomas with focal glandular features; 4 adenocarcinomas with focal squamous features; and 2 small cell carcinomas, one with glandular and the other with squamous features. Abnormal distributions of desmosomes in squamous cell carcinomas and of polarity of tumour cells in adenocarcinomas are described.