An immuno-electron microscopic study on intracellular localization of thyroglobulin (TG) in the thyroid gland in...

Intracellular localization of thyroglobulin (TG) using a pre-embedding diffusion technique and an indirect localization sequence has been made in human thyroid obtained from 20 patients with treated Grave's disease. Both antibodies, anti-human TG-rabbit IgG F(ab')2 and anti-rabbit IgG F(ab')2-goat IgG F(ab')2 fragments easily penetrated the cytoplasm of follicular cells which were dissociated by RPMI-1640 solution containing collagenase, dispase, and deoxyribonuclease. With light microscopic observation of semithin sections positive immuno-reaction for TG was demonstrated as fine granular deposits in the cytoplasm of the dissociated cells. In electron microscopic studies, intracellular antigen was well circumscribed within certain cell organelles in all cases with the positive immuno-reaction for TG being observed in perinuclear space, rough endoplasmic reticulum, Golgi complexes, secretory granules, and reabsorbed colloid droplets. Content of positive immuno-reaction product differed somewhat from one case to another and from one follicle to another even in the same case. There was no immunoreaction product in nuclei, mitochondria, lysosomes, and lipofuscin-like granules.