Fig. 2.

In situ hybridization of Twist1, Hand1, and Hand2 in sagitally sectioned E10.5 day mouse embryos. Expression is observed within a broad domain of mesodermally and neural crest-derived cells that make up the craniofacial, cardiac, sympathetic, and enteric nervous system as well as lateral mesoderm derived organs. Given the broad overlap of expression of Twist-family genes during development and the ability of the coded proteins to form transcriptional complexes modulation of where these genes are expressed as well as levels of overall expression are critical to normal development