Release of cyclic AMP from the chicken thyroid stimulated with TSH in vitro

The thyroid lobes excised from one-day-old or 13-day-old chickens were incubated with or without TSH, and cAMP in the medium was determined. TSH induced the release of cAMP from thyroid lobes, resulting in the increase of cAMP concentration in the incubating medium. The release of cAMP into the incubating media in the presence of TSH from the thyroids of the chickens which were pretreated with TSH neonatally was more marked as compared to that from the thyroids of the control chickens. The light and electron microscopic examination of the thyroid lobes incubated with TSH showed that the morphological changes such as colloid droplets formation and enlargement of endoplasmic reticulum were induced.