Abstract
In previous work 1 we found that intraperitoneal injection of an extract made from Armour's anterior lobe powder causes the thyroid gland of the larvae of Ambystoma tigrinum to display its functional phase in a typical manner long before it is displayed in normal animals and linked with the progress of metamorphosis in the same way as it is in normal metamorphosis. Exactly the same result we obtained by injecting, intraperitoneally, an extract of anterior lobe powder prepared in our own laboratory by the method described in Article I of this series. Illustrations are required to demonstrate satisfactorily these results and will he published in a more complete article. The main results will be summarized here.
The animals used are the same as those discussed in Article I of this series. Larvae of the eastern as well as of the western race (Utah axolotle) of Ambystoma tigrinum were examined. The thyroids of 16 experimentals and 11 controls were examined. The thyroids were studied fresh, stained or unstained, by a method described fully in a previous article. 2 Three representative thyroids will be discussed here.
In one larva (CCXCIV b 2) the cells of the thyroid were found distinctly changed towards increased functional activity, although the animial had received only 3 injections. The height of the cells was increased, the number and size of the neutral red granules was larger than in the controls (and in normal standard animals in general) and the intensity of the neutral red stain was distinctly greater. This animal showed only a few signs of metamorphosis.
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