Responses to thiourea and to surgical thyroidectomy by the autotransplanted pituitary gland in the red spotted newt

Abstract

Two tests of thyrotropic function were conducted on autotransplanted pituitary glands in red spotted newts, Notophthalmus (Diemictylus, Triturus) viridescens viridescens, Rafinesque. In the first of these, the engrafted newts together with intact control animals were maintained in aqueous solutions of thiourea for 150 days. A marked goitrogenic response was seen in half the intact animals and in slightly more than a third of the animals with autotransplanted pituitary glands. In the second test, other newts with autotransplants and newts with intact pituitary glands were kept in thiourea and were also thyroidectomized surgically. Representative groups were killed at 15, 30 and 60 days after thyroidectomy. Thyroidectomy cells appeared in most of the intact and autotransplanted pituitary glands of newts killed at 30 and 60 days after thyroidectomy but not at 15 days. In similar tests mammalian glands have failed to support either goitrogenesis or the formation of thyroidectomy cells. It follows, then, that the transplanted pituitary gland of the newt is more active thyrotropically than those of the mammals thus far examined. Reasons for this difference are discussed.