Expression Profiling by Systematic High-Throughput In Situ Hybridization to Whole-Mount Embryos

The genome of a given organism is considered in biology as the fundamental invariant (1 ). It is virtually the same throughout lifetime and, to a lesser extent, over generations. By contrast, genetic information is expressed in complex and ever-changing temporal and spatial patterns throughout development and differentiation. The description and analysis of these patterns is crucial to elucidate the functions of genes and to understand the network of genetic interactions that underlies the process of normal development.