Circannual rhythms in the activity of the parathyroid-gland and ultimobranchial body cells of the frog Rana-temporaria (Anura, Amphibia)

Abstract

The annual activity of the parathyroid gland cells and those of the ultimobranchial body cells of the frog Rana temporaria is quantitatively investigated by a morphometric study. A cosinor analysis shows a periodic succession of different parameters. The secretory activity of the parathyroid cells starts after a maximal value of external temperature in July. This activity is followed by an increase of plasma calcium which seems to induce the activity of the ultimobranchial cells.