Medullary carcinoma of the human thyroid in monolayer culture.Morphological and cytochemical correlations

Mechanically or enzymatically dissociated cells from three human medullary thyroid carcinomas (MTC) were grown in monolayer culture for periods up to seven months. Cultures of each tumor contained clusters of small epithelial-like cells which were readily identified by phase contrast microscopy. Immunocytochemical studies and electron microscopy showed that these cells contained abundant calcitonin and numerous secretory granules. Amine-storing mechanisms were also demonstrable in these cells by formaldehyde-induced fluorescence. Homogeneous cultures of epithelial-like cells showed no evidence of transitions into fibroblast-like cells. Addition of thyroxin to the tissue culture medium appeared to promote survival of epithelial-like cells in cultures of one tumor. The ability to morphologically recognize cultured cells with endocrine activity should facilitate establishment of human MTC lines for biochemical and physiological studies.