Editing African clawed frog (section)

=== Thyroid ===
The clawed frog liver responds to low temperatures by increasing production of [[DIO2|type II iodothyronine deiodinase]] {{clarify|text=through increased food intake|reason=The liver is increasing food intake? Increasing its own food intake? Or is this a psychogenic food intake increase?|date=August 2021}}. This in turn spurs the [[thyroid]] to increase [[T3 hormone|T{{sub|3}}]] to [[thermogenesis|increase body temperature]]. (This T{{sub|3}} increase also induces [[germ cell]] [[apoptosis]], mediated through genes left over from [[tadpole]] metamorphosis.)<ref name="Nakane-Yoshimura-2019" />

The effects of provocation of T hormone release are broadly differentiated by where it starts: If centrally, within the [[mediobasal hypothalamus]], then it stimulates seasonal [[testicle|testicular]] growth; if peripherally, then testicular regression and cold-season thermogenesis.<ref name="Nakane-Yoshimura-2019" />

These observations are regarded as widely applicable across vertebrate thyroid systems.<ref name="Nakane-Yoshimura-2019">{{cite journal | last1=Nakane | first1=Yusuke | last2=Yoshimura | first2=Takashi | title=Photoperiodic Regulation of Reproduction in Vertebrates | journal=[[Annual Review of Animal Biosciences]] | publisher=[[Annual Reviews (publisher)|Annual Reviews]] | volume=7 | issue=1 | date=15 February 2019 | issn=2165-8102 | doi=10.1146/annurev-animal-020518-115216 | pages=173–194| pmid=30332291 | s2cid=52984435 }}</ref>