Fig. 2. Left-right asymmetry of the ventral cord. (A,B) Wild-type animal. RIF neurons and AVG are labeled with odr-2::CFP (A), interneurons with glr-1::GFP, DA/DB motoneurons with unc-129::YFP (B). RIF axons extend anteriorly into the nerve ring crossing the ventral midline (arrowhead, RIF cell bodies are marked with asterisks. Later outgrowing interneuron axons cross over into the right axon tract at the same position (arrowhead in B). (C,D) Animal in which RIFR/L, SABVR/L and RIGR/L have been ablated, labeled with odr-2::CFP (C) and glr-1::DsRed (D). (C) Absence of the RIF neurons (compare with A); only AVG is still present. (D) Interneuron axons still cross over into the right axon tract (arrowhead). (E,F) Wild-type (E) and nid-1(ur41) mutant animals (F) labeled with a pan-neuronal marker (evIs111). (E) The majority of the axons extends in the right axon tract. (F) Almost half of the axons extend in the left tract in the nid-1 mutant (arrows). All animals show a ventral aspect with anterior towards the left. Scale bars: 10 µm.