Fig. 5. Loss-of-function mutations in RhoA and Rac disrupt peripheral glial development. Wild type and mutant embryos were labeled with anti-Neuroglian (green) and anti-HRP (red) to label peripheral glia and neurons, respectively. The anti-Neuroglian marker also labels the epidermis (asterisks). CNS is towards the left, anterior is towards the top. (A) A wild-type embryo at stage 16. The arrow shows peripheral glial sheaths extending along the peripheral nerve in the lateral region of the hemisegment. (B) A RhoA^k02107a homozygous mutant embryo shows a lack of peripheral glial sheaths in the lateral region of the embryo (arrows) and loss of glia at the CNS/PNS transition zone (arrowhead, compare with A). (C) A Rac1^J11 homozygous mutant shows lack of peripheral glial coverage of lateral axon tracts (arrow) and abnormal glial profiles in the ventral region (arrowhead). (D) The neuronal profile of the Rac1J11 mutant shown in C. The motor projections in the upper hemisegment are stalled (arrow), as are the lateral chordotonal sensory neurons (arrowhead). (E) A Rac2 homozygous mutant embryo shows lack of glial sheaths in the lateral region of the axonal tracts (arrow). (F) An Mtl mutant shows largely normal peripheral glial coverage of PNS axon tracts, with glial cells wrapping the lateral regions of the main ISN branch at stage 16 (arrow).

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