Fig. 2. Constitutively-active Racs induce ectopic morphogenetic structures in the PDE neuron. Fluorescence micrographs of PDE neurons from adult animals harboring an osm-6::gfp transgene. Anterior is towards the left and dorsal is upwards. The PDE cell bodies are indicated by arrowheads. (A) A wild-type PDE neuron displayed a single, unbranched axon extending to the ventral nerve cord (image is the same as in Fig. 1B). (B-F) PDE neurons of animals harboring a rac-2(G12V) transgene. (B) A rac-2(G12V) PDE neuron displayed ectopic axon branching and ectopic axons extending from the cell body. The ciliated dendrite (cilium marked by an arrow) also displayed ectopic branches. (C) A PDE neuron displayed a large, sheet-like plasma membrane extension (arrow). (D) A PDE neuron exhibited numerous thin, finger-like plasma membrane extensions (arrow). (E,F) A PDE neuron displayed two ectopic lamellipodia-like extensions (a and b) that were dynamic over time. (F) After 2 hours, one sheet-like extension (a) had ramified into two thinner neurite-like structures and another (b) had narrowed and elongated. New filopodia-like projections from the cell body not seen in E are indicated (c). Scale bars: 5 µm.