Very early developing embryos show distinct domains of gene expression. Although the whole embryo shows no obvious differences in cell types from one place to another, the frog gastrula has already set aside certain regions for distinct developmental fates. A special organizing region is marked by the blue stain; this region will later develop into the notochord, a transient stiff rod that is later subsumed into the vertebral column. Most of the rest of the "meat" of the animal, including muscles, kidneys, blood, skeleton is derived from the brown stained region. This early gastrulating Xenopus embryo is stained for Xnr3 (blue) transcripts and Xwnt-8 (brown) transcripts by in situ hybridization. Whole mount view from the vegetal pole.

This image is representative of work in the laboratory of Richard Harland in the Department of Molecular and Cell Biology.