Expression data from E12.5 ePet-EYFP rostral and caudal serotonin (5HT) neurons purified by flow cytometry

The 5HT system is organized into rostral and caudal populations with discrete anatomical locations and opposite axonal trajectories in the developing hindbrain. 5HT neuron cell bodies in the rostral subdivision migrate to the midbrain and pons and extend ascending projections throughout the forebrain. 5HT cell bodies in the caudal subdivision migrate to the ventral medulla and caudal half of the pons and provide descending projections to the brainstem and spinal cord. We used microarrays to determine genes expressed by both rostral and caudal 5HT neurons as well as genes that are differentially expressed between rostral and caudal 5HT neurons at E12.5 when axon pathfinding and cell migration are underway. E12.5 neural tubes were isolated from ePet-EYFP embryos and dissected into a rostral domain (mesecephalic flexure to pontine flexure) and a caudal domain (pontine flexure to spinal cord). After cell dissociation (details under growth protocol), cells were subjected to fluorescent activated cell sorting (FACS) to obtain 4 cell populations. R+ = rostral ePetEYFP positive 5HT neurons; R- = YFP negative non-serotonergic cells in the rostral neural tube; C+ = caudal ePetEYFP positive 5HT neurons; C- = YFP negative non-serotonergic cells in the caudal neural tube. 200,000 cells for each of the 4 cell types (R+, R-, C+, C-) were collected for RNA extraction and hybridization to Affymetrix Mouse 430 2.0 arrays.