Effects of TSH and cyclic AMP on the human thyroid cells cultured in a chemically defined medium

In a serum-free, chemically defined medium human thyroid cells elongated remarkably and resembled fibroblastic cells. They retained the cyclic AMP response to TSH and the supplement of medium with TSH or dibutyryl cyclic AMP permitted the preservation of epithelial nature by the cells. Cyclic AMP of the cells of epithelial nature was higher than those of fibroblastic appearance.