6A). experimentally proven that addition of exogenous Wnt5a proteins to the lifestyle moderate causes morphological adjustments in the larval epithelium expressing Ror2 also in the lack of T3. On the other hand, in the current presence of T3 where in fact the adult stem cells are shaped small intestine, we yet others previously showed that the larval epithelium mostly undergoes apoptosis, whereas the adult epithelium develops from a small number of undifferentiated cells C. These undifferentiated cells become histologically detectable as small roundish islets between the larval epithelium and the connective tissue around NF stage 60 (early stage of metamorphic climax) . The islets, which consist of a single or few cells at first, rapidly grow in size by active proliferation, invaginate into the connective tissue, and then differentiate into the single layer of adult epithelium as morphogenesis of intestinal folds proceeds. The adult epithelium after metamorphosis is rapidly renewed along the trough-crest axis of the intestinal folds  similar to that along the crypt-villus axis of the adult mammalian intestine , . These chronological observations imply that the small islets of intestine around stage 60 include the adult stem cells homologous to those in the mammalian intestine. In fact, increasing evidence indicates that mammalian intestinal stem cell markers such as Musashi-1 (Msi1) ,  and leucine-rich repeat-containing G protein-coupled receptor 5 (Lgr5) C are specifically expressed in the islets of intestine at and after stage 60 , . Thus, this amphibian model offers a valuable opportunity to understand how the adult stem cells and their niche are formed during normal development. The key advantage of this amphibian model is that the whole process of the larval-to-adult intestinal remodeling including the adult stem cell formation can be experimentally reproduced both and by 3,5,3-triiodothyronine (T3) , , a well-known causative agent of amphibian metamorphosis , , . In particular, in the intestine, numerous T3 response genes have been recently identified by microarray analyses C and provide us powerful clues to clarify molecular mechanisms underlying formation of the adult stem cells and their niche. We have previously shown by tissue recombinant experiments that the adult stem cells originate from the larval epithelium of the intestine at stage 57 before metamorphic climax . Since the larval epithelium at this stage is fully differentiated as a simple columnar epithelium mainly consisting of absorptive epithelial cells, goblet cells, and enteroendocrine cells  and does not include any undifferentiated roundish cells expressing the stem cell markers , , it should be concluded that at least partly differentiated intestinal epithelial cells become the adult stem cells around stage 60 . If so, the following questions arise: (1) what type of cells in the simple columnar larval epithelium have a potency to become the adult stem cells? (2) how do such columnar cells dedifferentiate into roundish stem cells and invaginate into the connective tissue by changing their morphology? To address these issues, we here focused on a Edotecarin Edotecarin Edotecarin non-canonical Wnt/planar cell polarity (PCP) pathway which has been reported to regulate cell polarity or migration in Edotecarin several organs ,  including the mammalian embryonic gut . Among T3 response genes identified so far in the intestine, there are Wnt5a and its receptors, frizzled 2 (Fzd2) and receptor tyrosine kinase-like orphan receptor 2 (Ror2) , all of which are members of the PCP pathway. To know whether Wnt5a signaling is really involved in the amphibian stem cell formation, we first examined by quantitative RT-PCR (qRT-PCR) Sox17 and immunohistochemistry the expressions of Wnt5a, Fzd2, and Ror2 in the small intestine during metamorphosis. We found that their expression profiles correlate with the adult epithelial development but not with the larval epithelial degeneration. Especially, morphological changes of larval absorptive epithelial cells that express Ror2 coincide well with the formation of adult stem cells, suggesting important roles of Ror2 in this process. Next, by using Wnt5a protein and its function-blocking antibody in the organ culture of intestine animals were approved by the Animal Use and Care Committee of Nippon Medical School. Quantitative Real-time Reverse Transcription-Polymerase Chain Reaction (qRT-PCR) Total RNA was extracted from the small intestine of wild-type.