Temperature, thyroxine, and induced metamorphosis in tadpoles of a primitive frog, Ascaphus truei.

摘要: To understand the environmental factors and endocrine mechanisms which regulate extended period (2 to 4 years) of larval development in Ascaphus, effect temperature thyroxine (T4 by immersion) on metamorphic changes tail, limb buds, operculum, anal fold, oral disc, teeth were studied premetamorphic prometamorphic tadpoles. (1) Control tadpoles did not undergo change at any temperatures tested. (2) When kept solutions 5 degrees, there no developmental morphology, 18 20 degrees showed significant 6 days, but was a high mortality higher T4 concentrations. The optimum is about 10 completed 3 weeks. (3) less sensitive than most responsive tissues are tail tissue shows lowest sensitivity. (4) Duration exposure hormone concentration also affect growth or regression tissue.