Thyroid photoperiod and gonadal regression in the common myna Acridotheres tristis.
In the common myna, extirpation of the thyroid glands inhibited seasonal development of the testes of birds maintained under normal length days, but full development, similar to sham-operated birds, resulted when maintained under 15L:9D. Further, thyroidectomy delayed and reduced the rate of gonadal regression when performed in 15L:9D exposed birds having fully developed testes. The thyroid-gonad relationship exhibited in the common myna is of great adaptive value to the bird, especially in the subtropics, where sudden fluctuations in environmental temperature (due to heat wave/hail storm) may lead to sharp alterations in thyroid activity.
D000818:Animals; D001717:Birds / Q000502:physiology*; D008027:Light; D008297:Male; D010507:Periodicity; D012621:Seasons; D013737:Testis / Q000502:physiology*; D013961:Thyroid Gland / Q000502:physiology; D013965:Thyroidectomy