Fig. 3. Serial homology in cell identity between specific OP sublineages and O and P sublineages is shown by injection of rhodamine dextran lineage tracer. The labeled embryos were fixed and dissected at stage 9. The clonal origin of the labeled cells is shown at the lower right corner of each panel. The pattern elements derived from the op.aa cell (A) in the rostral segments are homologous to the pattern elements derived from the o.aa cell (B) and the p.aa cell (C) in more posterior segments. The pattern elements derived from the op.ap cell (D) in the rostral segments are homologous to the pattern elements derived from the p.ap cell (E) in more posterior segments. The pattern elements derived from the op.pa cell (F) in the rostral segments are homologous to the pattern elements derived from the o.ap cell (G) in more posterior segments. The pattern elements derived from the op.pp cell (H) in the rostral segments are homologous to the pattern elements derived from the p.p cell (I) in more posterior segments. See text for detail. CR, crescent neuron cluster; PV, posterior ventral neuron cluster; AD, anterior dorsal neuron cluster; WE, wedge-shaped neuron cluster; mpg, medial packet glia; c.f.3, cell floret 3; t., tubular structure homologous to the nephridial tubule (n.t.) in midbody segments (see text for detail); epi., epidermis. Orientation of the specimen is the same as in Fig. 2. Scale bar: 20 µm.