Fig. 5. (a-c) Electron micrographs of follicular cells in animals exposed to 50 Hz EMF. The significant features are: a giant colloid droplet (carets) in a; a large colloid droplet (carets) surrounded by lysosomes in the central part of a thyrocyte in b and near the basal membrane (carets) in c; pleomorphic lysosomes (ly) in the apical cytoplasm in b; rough endoplasmic reticulum (er) with amorphous contents of different density and dilated cisternae in a, b and c. c, colloid; am, apical membrane; bm, basement membrane; pf, parafollicular cell. All photomicrographs are of the same magnification. Scale bar, 1 µm.