Whole Mount In Situ Hybridization in Xenopus.

Whole mount in situ hybridization is a method of viewing gene expression in intact tissue, developing embryos, and tadpoles. It uses labeled, in vitro transcribed RNA probes to specifically bind to mRNA through complementary base pairing. Unlike protein detection, making an antisense RNA probe requires only knowledge of the corresponding coding sequence. It is therefore accessible for any gene, and has contributed hugely to our understanding of how genes shape development. This protocol highlights the key considerations balancing fixation and permeabilization to preserve tissue while allowing the probe to enter cells, and to optimise signal-to-noise for the colorimetric reaction.