Figure 10

Lhx9 triggers a ventral shift to the longitudinal dI2^Lhx9 axons. (A, B) An open-book preparation of the neural tube in which the commissural dI1 axons express GFP and dI2 axons express taumyc (EdI1::Gal4 + UAS::GFP; EdI2/V1::Cre + pCAGG-LoxP-STOP-LoxP-taumyc). The contra-lateral side of the neural tube is shown. dI2 axons turn longitudinally, at the lateral funiculus (LF), and form a fascicle that is located dorsally to the dI1 fascicle. Ectopic expression of Lhx9 in dI2 neurons (EdI2/V1::Gal4 + UAS::GFP_UAS::Lhx9) resulted in dI2^Lhx9 axons fasciculating with dI1 axons at the contra-LF. (C) Schematic illustrations of the co-fasciculation phenotype of dI2^Lhx9 neurons. The green and red arrows point to the axons of dI1 and dI2 neurons according to the color code that is indicated in each illustration. Scale bars: 150 μm (A, C, D); 200 μm (B).