The Hox genes are a family of highly conserved transcription factors that are critical during embryonic development. Although the function of Hox genes is to pattern the embryo from head to tail, the mechanism by which Hox genes do this is unknown. Elucidating the mechanism for Hox gene function can provide insights into how morphologies are formed in a variety of organisms. I am investigating the role of Hoxd13 in patterning the colon in the developing chick. We virally misexpressed the chick ortholog, cHoxd13, in the midgut mesoderm of the chick to validate that transformation to hindgut morphology would occur. To determine if the role of Hoxd13 has been conserved since the evolution of the cartilaginous fish, we will misexpress the skate ortholog of the gene, LeHoxd13, in the chick embryo and check for transformation to colon morphology. To do this, we are constructing a retrovirus that will express the skate Hoxd13 gene in the chick embryo. If we can show that hindgut character is induced in the midgut with viral misexpression of cHoxd13 and LeHoxd13, our hypotheses that Hoxd13 serves to pattern the embryonic colon, and that its function is evolutionarily conserved, will be supported