Fig. 7. Ubiquitous expression of ectopic Sema3a1 induces abnormal outgrowth by CaP axons but not MiP or RoP axons. Wild-type biotin-labeled donor cells (black) were transplanted into unlabeled hsp70:gfp-sema3a1-myc transgenic hosts. Hosts were heat induced and donor motor axons assayed with mAb Znp1 (brown). (A) Wild-type donor CaP in a heat induced wild-type host extended normally. (B) Wild-type CaP neuron in a hsp70:gfp-sema3a1-myc transgenic host branched (arrowheads) aberrantly following heat induction of Sema3a1. (C) Transverse section showing a donor CaP axon extending aberrantly into lateral regions of the myotome (arrowhead) in a hsp70:gfp-sema3a1-myc transgenic host following heat induction of Sema3a1. (D) A donor MiP axon extended normally in a hsp70:gfp-sema3a1-myc transgenic host following heat induction of Sema3a1. Asterisk indicates a non-motoneuron donor cell. (E) A donor RoP axon extended normally in a hsp70:gfp-sema3a1-myc transgenic host following heat induction of Sema3a1. Scale bars: 20 µm.