A study from 2006 revealed a complicated and tightly controlled HOX gene expression pattern along the body axis of the developing Drosophila embryo. This image shows beautiful staining for seven different genes!
Genomic Evolution of Hox Gene Clusters
Derek Lemons and William McGinnis
Science 29 September 2006:
Vol. 313 no. 5795 pp. 1918-1922
Confocal image of septuple in situ hybridization exhibiting the spatial expression of Hox gene transcripts in a developingDrosophila embryo. Stage 11 germband extended embryo (anterior to the left) is stained for labial (lab), Deformed (Dfd),Sex combs reduced (Scr), Antennapedia (Antp), Ultrabithorax(Ubx), abdominal-A (abd-A), Abdominal-B (Abd-B). Their orthologous relationships to vertebrate Hox homology groups are indicated below each gene.