The Localization of Radioactivity in the Orbit and the Thyroid Gland after Injection of S³⁵‐labelled Thyrotropin into the Carotid Artery of Guinea‐pigs

Abstract

Sonenberg and co-workers (1 952) (5) have studied the fate of Sa5-labelled pituitary extract with thyrotropic and gonadotropic activity injected into oneday-old male chicks. I n the same way labelled Sa5-bovine serum albumin was used as a control substance. The radioactivity was determined in different organs at different times after the injection, and significant concentrations were found in the thyroid, gonads and liver. The orbital contents did not show any significant accumulation of radioactive substance.I t has been shown that thyrotropin administration significantly increases the uptake of SWabelled sulphate by the orbital tissues (2) and that the pituitary factor responsible for the stimulation is