This dataset was used to as a filter to annotate the results from another experiment (GSE29791). We used these results to find genes that were enriched in the head regions. In this way, we could eliminate more ubiquitously expressed genes. Overall design: St. 18 embryos were bisected and RNA was collected from head and tail fragments. 3 individual heads and 3 tails were run, as well as 1 pool of heads and 1 pool of tails comparison of gene expression profiles for tissues