Figure 1.

Dll expression in representative protostomes. (a) Lateral view of a late stage Precis coenia butterfly embryo stained with the Dll antibody. Arrows (➞) point to the distal tips of the left abdominal prolegs. Dll expression is detected in central nervous system in the brain (br) and in the ventral nerve cord (➤). (b) Higher magnification image of abdominal prolegs (➞) from an embryo similar to that shown in a. (c) Ventral view of a late stage Peripatopsis capensis onychophoran embryo stained with the Dll antibody. The antennae (ant), oral papilla (➤) and lobopods express Dll. The lobopods shown in higher magnification in e are indicated with ➞. (d) Right halves of two segments from a young P. capensis embryo stained with the Dll antibody. Dll expression is detected in the ectoderm of the presumptive lobopods prior to the formation of visible buds. (e) Higher magnification view of the lobopods indicated in d. (∗) The neurogenic ectoderm, which also expresses Dll. (f) Polychaete annelid Chaetopterus variopedatus, ventral view of larva just prior to metamorphosis. Dll expressing cells are visible in parapodial rudiments (➞), antennae (out of focus on opposite dorsal surface, (➤), prospective feeding organs (⊓), and in the neurogenic ectoderm (∗). (g) C.variopedatus, same specimen at a higher magnification, showing Dll reactive ectodermal nuclei in prospective distal cells of the anterior parapodia (➞) and in the neurogenic region (∗). (h) Later stage C. variopedatus larva showing staining in distal portions of two anterior parapodia (➞). Anterior is to the left in all panels. (Bars = 0.1 mm.)