Studies on corticoid action on the toad tadpole tail in vitro.

The effect of adrenal corticoids on the shrinkage of tail segments from Bufo bufo japonicus tadpoles was studied in vitro. Deoxycorticosterone acetate (DCA) was effective in accelerating the shrinkage of tail segments if thyroxine (T4) or triiodothyronine (T3) was present in the medium. The shrinkage caused by DCA was dose dependent. In the absence of thyroid hormone, DCA did not induce tail resorption. Shrinkage of tail segments induced by DCA and T4 was blocked by prolactin. Among the steroid hormones testes in vitro, aldosterone and corticosterone exhibited a potent activity in accelerating shrinkage of tail segments in the presence of T4. The nature of the corticoid action is discussed.