Fig. 6. Retinal axons with impaired activity of the Xena/XVASP proteins generated a limited number of filopodia-like processes and only rarely a few branches. (A,B) In vivo time-lapse sequences of terminal arborizations of control GAP-GFP-expressing (A) and of FP4-Mito-RFP+GAP-GFP-expressing (B) retinal ganglion cell (RGC) neurons in the tectum. Growth cones were photographed every hour during the 3 hours following the entry of retinal axons in the tectum. White arrowheads point to growth cone filopodia and black arrowheads to branches. (C,D) Diagrams of control GAP-GFP-expressing (C) and FP4-Mito-RFP+GAP-GFP-expressing (D) axonal terminal arborizations. Primary (blue), secondary (green) and tertiary (red) branch segments are illustrated. Scale bar: 32 µm in B for A,B.