LAUSR

During Xenopus metamorphosis, most tadpole organs remodel from the larval to adult form to prepare for adaptation to terrestrial life. Organ culture serves as an important tool for studying larval-to-adult organ remodeling independent of the effects of other parts of the body. Here, I introduce a protocol for organ culture in vitro using the Xenopus laevis tadpole intestine before metamorphic climax. During culture in the absence of exogenous 3,3',5-triiodo-l-thyronine (T3), the most potent natural thyroid hormone, the intestine remains in its larval state without any metamorphic changes. In contrast, when T3 is added to the culture medium, the larval epithelium undergoes apoptosis, whereas adult stem cells appear, actively proliferate, and finally generate the differentiated adult epithelium within a week. At the same time, the surrounding nonepithelial tissues also develop. Thus, this culture model is useful for clarifying the control mechanisms of apoptosis in larval tissues, formation of adult stem cells, and cell proliferation and differentiation of adult tissues, all of which occur in harmony during natural metamorphosis. Moreover, a procedure for tissue recombination combined with organ culture provides a platform for investigating complex tissue interactions during organ remodeling. Such tissue recombination experiments will help to reveal the important role of nonepithelial tissues in larval epithelial apoptosis and/or adult stem cell development in the X. laevis intestine.