Overlapping imprinting of thyrotropic (TSH) and gonadotropic (FSH, LH) hormones in cultures of newborn rat testicles and ovaries.

Cultured gonadal cells of male and female newborn rats increase their hormone-binding capacity after the first treatment with gonadotropin. The imprinting effect of thyrotropin, similar in structure to gonadotropin and binding to its receptors, was found more pronounced in testicular than in ovarial cells. In the latter a negative imprinting with TSH was observed. Results corroborate the view that hormone receptors are present in early stages of ontogenesis and prove the development of imprinting also in cultured target cells.