Continued expression of the chicken caudal homologue in endodermally derived organs

We show that the CHox-cad gene is continuously expressed throughout embryogenesis from Days 1 to 14 of development. In the adult chicken, CHox-cad appears to be expressed exclusively in the gut. Genomic Southern blot hybridization experiments suggest that there may be only a single CHox-cad gene per haploid genome from which RNAs of 2.9 and 1.6 kb are transcribed. In situ hybridization to sections of 80-hr to 12-day chick embryos with a CHox-cad probe reveals that this gene is expressed at high levels in organs of endodermal origin: the developing liver, pancreas, lung, and in the epithelial lining of the entire intestine. By Day 16 of development, CHox-cad signals are observed in the epithelial lining of the gut but no longer in the other endodermally derived organs. The coincidence of CHox-cad expression with the onset of development of these endoderm-derived organs may indicate an important role for that gene during the early steps of organogenesis.