Demonstration of hormonal sensitivity in gynaecomastic tissue by thymidine incorporation in vitro.

Gynaecomastic tissue from six patients were tested for oestrogen and testosterone sensitivity as measured by thymidine incorporation in tissue fragments in vitro. The DNA synthesis of the cultures was increased in tissue from five out of the six patients under the influence of oestrogen, whereas it was increased in tissue from only one patient under the influence of testosterone. The results are discussed in relation to the medical histories of the patients and hormonal excretion studies done by others.