Markers that uniquely identify the cells of the NB3-7 lineage were used to examine the serotonin expressing cell lineages.
Ecol\lacZeg-P289 is expressed in ventrolateral cell clusters of the ventral nerve cord. These clusters contain the ventrolateral serotonergic neurons. Ecol\lacZeg-P289 is also expressed in small groups of cells lying close to the midline in each hemisegment. Many of these cells are serotonergic cells..