Thyroxine, Thiouracil and Embryonic Respiration in White Leghorns

INTRODUCTION IN THE latest work on the respiratory metabolism of chicken embryos (Romijnand Lokhorst, 1951) the authors have suggested the supposition that thyroid hormone and antithyroid substances would have influence on the metabolic rate of the embryos during the incubation period. As far as we can find literature on this subject is rare. After introducing thyroxine (0.025 microgram) into the air space on the 8th day of incubation, Hanan (1928) found a marked increase of CO2 production, extending over a period of about 3 days, which was followed by a period of depression below normal, lasting about 8 days. A correct interpretation of his results could not be given. Our experiments have been undertaken in order to investigate the effect of thyroid hormone and antithyroid substance on the respiratory metabolism of chicken embryos during the incubation period. Moreover some data about the influence on body weight, thyroid weight and histological . . .