Tissue sensitivity to thyroid hormone in athyroid Xenopus laevis larvae.
Tadpoles that spontaneously arrest development and remain as larvae occur occasionally in Xenopus laevis populations. These non-metamorphosing tadpoles continue to grow, and they develop into grossly deformed giant individuals which come as close as any anurans to being truly neotenic. Giant X. laevis tadpoles that fail to metamorphose lack thyroid glands. In this study, the hypothesis that the tissues of these tadpoles nevertheless remain thyroid hormone sensitive was tested, by exposing isolated tadpole tail tips to exogenous thyroid hormone in tissue culture. The tail tips from giant tadpoles significantly shrank in response to the thyroid hormone treatment, showing that their tissue was still capable of metamorphosis. However, the amount of shrinkage was less than that observed in tail tissue from normal tadpoles. It was hypothesized that complete induction of metamorphosis may not be possible in the giant tadpoles due to a disproportionate growth and development of tissues and organs.
Rot-Nikcevic
Irena
I
Department of Anatomy and Neurobiology, Dalhousie University, Sir Charles Tupper Medical Building, 5850 College Street, Halifax, Nova Scotia, B3H 1X5, Canada. nikcevic@dal.ca
Wassersug
Richard J
RJ
D000818:Animals; D017209:Apoptosis / Q000502:physiology; D007814:Larva / Q000378:metabolism; D009928:Organ Specificity / Q000502:physiology; D013623:Tail / Q000378:metabolism; D013961:Thyroid Gland / Q000378:metabolism*; D013963:Thyroid Hormones / Q000378:metabolism*; D014981:Xenopus
D013963:Thyroid Hormones