[Age and biorhythms of the histophysiologic indices of the thyroid gland]

Rhythmic changes of several histophysiological parameters of the thyroid gland was studied in 144 A/He mice of three age groups: young immature, mature adults and ageing animals. The multicomponent nature of the rhythmic changes was found for each index; it included the circadian component, as well as infradian oscillations. The leading role of the circadian component in the establishment of the biorhythms of the organ functioning was shown, whereas ontogenetic changes were chiefly associated with the ultradian components' attenuation.