Gene Expression Analysis in Developing Embryos: In Situ Hybridization

In situ hybridization (ISH) is a technique that offers the ability to detect, and assay for alterations in, the spatial distribution of gene transcripts in an organism and is thus an invaluable tool to understanding the molecular basis during various developmental processes. Changes at the molecular levels consequent to toxicological perturbations and characterization of the expression of new or uncharacterized genes can be performed at the spatial and temporal levels with relative ease, speed, and specificity. Knowledge of expression pattern of specific genes allows one to formulate hypotheses of possible functions, molecular partners, and signaling pathways. We describe a procedure for ISH analysis of developing whole mouse embryos with the use of nonradioactive in vitro transcribed antisense RNA (riboprobes) and detected indirectly by a colorimetric reaction.