Any of the zygotic genes expressed subsequently after segmentation genes, and whose function specifies the fate of the cells in each segment of the fruit fly embryo.
In Drosophila the cells in each segment will differentiate based on their cell fate already determined early in fruit fly embryo development. The Drosophila contains two clusters of homeotic selector genes, the antennapedia complex and the bithorax complex. It is responsible for the proper number and placement of embryonic segment structures such as legs, antennae and eyes.
Also called: homeotic gene or Hox gene
See also: segmentation gene.