Xenbase Image ID: 175532

Figure 1. Biological context. The High Thyroid Hormone Period (HTP), that marks the end of tadpole stage (blue rectangle) in X. tropicalis, ignites metamorphosis and the resorption of larval tissues (such as tailfin). In Axolotl, the HTP does not induces tailfin resorption. “pre-HTP” animals will refer to class 3 Axolotl [as defined by Rosenkilde et al. (23)], when limb buds start growing (around 2 weeks post-hatching). At this stage, endogenous TH level is low and thyroid gland starts releasing TH. “mid-HTP” animals refer to class 8 Axolotl, with four toes on hind limbs (between 32 and 48 days post-hatching). This stage corresponds to the highest level of endogenous T4. “post-HTP” animals refer to class 12 Axolotl (around 3 months old), where T4 endogenous level dropped significantly. X. tropicalis tadpoles were staged according to the normal table of Xenopus laevis (Daudin) of Nieuwkoop and Faber (24). The TH levels are schematized from data of Leloup and Buscaglia (25) for Xenopus and of Rosenkilde et al. (23) for Axolotl. Digital paintings were carried out with BLENDER v2.8b. Image published in: Kerdivel G et al. (2019) Copyright © 2019. This image is reproduced with permission of the journal and the copyright holder. This is an open-access article distributed under the terms of the Creative Commons Attribution license Larger Image Printer Friendly View

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