Molecular Mechanism and Evolutional Significance of Epithelial–Mesenchymal Interactions in the Body‐ and Tail‐Dependent Metamorphic Transformation of Anuran Larval Skin

摘要: The epidermis of an anuran larva is composed apical and skein cells that are both mitotically active self‐renewed through larval life. In contrast, the adult frog, with typical stratified squamous epithelium germinative basal, spinous, granular, cornified cells, histologically identical to mammalian epidermis. Two important issues have not yet been addressed in study development skin. One origin basal other mechanism by which transformed into a region‐ (body‐ tail‐) dependent manner. cell lineage relationship between epidermal was determined examining expression profiles several genes expressed specifically and/or differentiation cultured presence thyroid hormone (TH). Histological analyses using markers led identification skin transformation center (STC) where conversion counterpart taking place. STC emerges at specific place body stage development. progressively “moves” “invades” adjacent region trunk as develops, converting preadult skin, but never tail region. requires epidermal–mesenchymal interaction. genesis suppressed due influence underlying mesenchyme PDGF signaling one molecular cues interactions. addition, unique feature metamorphosis presented referring vertebrates. comparisons among vertebrate species strongly suggested similarity teleost fish tetrapod species. Based on these similarities, evolutional significance proposed. Finally, studies reviewed reveal relation TH‐TR‐TRE signaling. results suggest new aspects biological TH, also enable us envision concerted regulations gene frame network responsible for metamorphic remodeling tissues. present review will contribute understanding region‐dependent anurans from only point view, provide way understand TH anurans.