Publication Date


Document Type


First Advisor

Prahlad, K. V.||Norstog, Knut, 1921-||Graves, Lynn B.

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Biological Sciences


Metamorphosis; Thyroid hormones


Uptake of ¹⁴C thyroxine (T₄) and ¹²⁵I triiodothyronine (T₃) reached an early maximum in the gill, liver, skin, and tail tissues of both the Mexican axolotl (Ambystoma mexicanum) and the tiger salamander (Ambystoma tigrinum). Following a single injection of ¹⁴C T₄ or ¹²⁵I T₃. The amount of label present in the gill, liver, skin, arid tall (gill, tail, and body only in embryonic tissue) was measured with a liquid scintillation counter. In some experiments the label was identified and separated with thin layer chromatography before liquid scintillation determinations so that the amount of label in the form of the injected hormone could be more accurately quantified. Hypothalamus, pituitary, thyroid, and other neural tissue uptake of 125I T₃ was also measured in the larger animals. The amount of hormone present per mg of tissue was in the order liver>> skin> gill and tail. The gill and tail tissues showed a peak uptake of ¹⁴C T₄ and ¹²⁵I T₃ at 3 hours, followed by a slow decline. In embryos the gill and tail tissues also exhibited an early peak uptake followed by a decline while the body tissues showed a continual increase. Thyroid tissues showed a continual increase in the amount of label present while neural and hypothalamic tissue showed a build up of label to a high value. The pituitary, however, showed an early peak, followed by a decline, which then increased to a medium level value. The above mentioned results seem to indicate that the thyroid hormones are taken up by some of the tissues, utilized, and then released, being no longer needed to maintain metamorphic changes. The pattern of pituitary uptake may indicate that the pituitary is being influenced directly by the hormone.


Includes bibliographical references.||Includes illustrations.


viii, 54 pages




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