During ventral enclosure of the epidermis, VAB-1::GFP was expressed in clusters of cells of the head and tail regions. In the head region, VAB-1::GFP was expressed in clusters of presumptive neuronal cells. Early in enclosure these cells appear to lie beneath the epidermal leading cells; later in enclosure, the VAB-1expressing cells lie anterior to the leading cells. VAB-1::GFP was not detectably expressed in the epidermal leading cells at any stage during ventral enclosure. In the posterior of the embryo, VAB-1::GFP was expressed in several cells, including QV5 and the ventral
hyp7 cells posterior to the rectum; VAB-1::GFP was also expressed in several pharyngeal cells. In late embryogenesis and throughout larval and adult development, VAB-1::GFP was localized to the axons of many neurons throughout the nervous system. Thus, in most stages following gastrulation, VAB-1::GFP is widely expressed in the developing nervous system.