[Ultrastructural characteristics of the cells of human medullary thyroid cancer].

Eight medullary carcinomas of the human thyroid gland were examined electron microscopically for identification of cell types forming these tumors. The diagnosis was based on classical histological criteria including a positive reaction for amyloid and impregnation according to the method of De Grandi specific for C-cells. The human medullary carcinoma of the thyroid gland was found to contain dark, light, and intermediate tumor cells. The ultrastructural features of these types of cells suggest that they may be regarded as being at different stages of the intensity of synthesis processes more in the light cells. Amyloid production in this type of cancer is associated with tumor cells.