TRANSEPIDERMAL POTENTIAL DIFFERENCE: DEVELOPMENT IN ANURAN LARVAE.

Skin from bullfrog tadpoles does not show the potential difference characteristic of adult frog skin until several days after the emergence of the forelimbs, presumably because the mechanism for active sodium transport is absent or nonfunctional. Exposure to low concentrations of thyroxine accelerates appearance of the transepidermal potential difference at rates which are related to the dosage. This system may provide a new basis for evaluating the importance of specific biochemical mechanisms in active sodium transport.