This chapter describes a nonradioactive method for the localization of mRNA in whole mouse embryos. It employs riboprobes labeled with digoxigenin, a steroid-like moiety not found in animal tissue. Digoxigenin-containing probe is visualized with a conjugate of antidigoxigenin Fab and alkaline phosphatase and colorimetric staining. The results are visualized in three dimensions, hence subtle patterns can be visualized without laborious sectioning.
