Ultrastructural observations on the droplets of experimentally-induced goitres in Xenopus laevis with especial reference to the development of uhlenhuth colloid cells

Summary Goitres were induced in tadpoles and young toads of Xenopus laevis Daudin by prolonged immersion in aqueous solutions (0.005% or 0.01% w/v) of potassium perchlorate, potassium thiocyanate, thiourea or propyl-thiouracil. Various categories of single membrane-limited droplets were induced and these are described. Also some of the goitrous cells showed an accumulation of colloid droplets leading to the formation of Uhlenhuth colloid cells. The development and significance of these cells in the amphibian goitres is considered.This work was carried out during the tenure by one of us (R. C.) of a Medical Research Council Scholarship and forms part of a programme of research in amphibian thyroid physiology supported by the Medical Research Council to whom we are indebted for their generous assistance.