Immunodetection of β-catenin accumulation in the nucleus is the most direct and reliable method to determine the intensity and the spatial/temporal patterns of Wnt-dependent signaling activity. Due to the large size of theXenopusembryo, staining must be done on sections. We present here a simple protocol to prepare cryosections and produce high-quality images of the early embryo using immunofluo-rescence. We also provide comments on various conceptual and technical issues from fixation to image collection, which may assist in optimizing immunodetection in embryos and tissues beyond the specific scope of β-catenin localization.
