鶏に於ける甲状腺機能の季節的消長に就て

概要

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The thyroid function in the fowls was measured throughout a year to determine the seasonal pattern of thyroid activity. The thyroid activity was determined with serum protein-bound iodine by the method described by BARKER. The collections of serum were made in the latter part of every month. Serum protein-bound iodine was at the maximum level of 8.4γ% for females in the experiment in July and of 7.9γ% for males in May. A further decline occurred in the latter part of October to the minimum values of 5.1γ% for females and 5.3γ% for males. During winter and spring, however, the range of the thyroid secretion was too small to permit one to distinguish any large difference. Sex differences were observed in the seasonal rhythum of thyroid secretion.It may be possible that the thyroid hormone secretion level was influenced by seasonal variation in environmental temperatures reported by MANSFELD, in the intensity and duration of daylight, in egg or sperm production, in moulting and etc.