Anterior Pituitary Preparations Research Articles

A Retardation in the Rate of Metamorphosis of the Colorado Axolotl by Injection of Anterior Hypophyseal Fluid

ABSTRACT In 1922, the author with I. P. Smith, reported in a brief abstract that the intraperitoneal injection of fresh anterior hypophyseal fluid slowed decisively the environmentally-produced metamorphosis of the Colorado axolotl (A. tigrinum). In a second abstract (Smith and Smith, 1923), it was shown that the injection of fresh anterior lobe fluid also diminished the metamorphic stimulus afforded by thyroid administration. Since the appearance of these abstracts, Hogben (1923) has reported opposite effects, namely, that the intraperitoneal injection of a commercial anterior lobe extract caused a rapid metamorphosis of the normal unoperated Mexican axolotl (A. tigrinum) and even of thyroidectomized individuals of this species. Spaul (1924 a), using the same commercial preparation as Hogben, confirmed the results of this investigator in the unoperated axolotl and found in addition that the metamorphic rate of the tadpole was greatly accelerated. More recently, Spaul (1924 b) tested some twelve commercial anterior pituitary preparations for the presence or absence of a principle which would metamorphose the axolotl. He found that only two of these produced what he terms “the appropriate response,” namely, metamorphosis ; the other ten gave negative results. He assumed that these ten preparations contained some inhibitory substance which prevented the principle inducing metamorphosis from expressing itself. The opposite assumption might seem as reasonable, namely, that the ten preparations, because of their great numerical majority, gave “the appropriate response,” and that the two preparations inducing metamorphosis contained some unusual substance giving an atypical response.