Figure 6

Figure 6

Morphometry of PyrN arbors formed in SM, SFGS, and SGC layers of tectum. (A) Dorsal view, whole-brain confocal image volume of a 7 dpf double transgenic Tg(id2b:gal4,uas:NTR-mCherry) larva injected at the embryo stage with a uas:egfp-caax plasmid to yield sparse genetic labeling. Note single EGFP-labeled neuron in each tectal lobe. (B) Higher magnification maximum projection of neuron labeled in right tectal lobe of larva in (A). Projection is shown from dorsal view, 0° Y-Axis rotation. Maximum projection of same neuron rotated −40° about the Y-axis, an orientation parallel to the tectal layers (B′). Maximum projection of same neuron rotated +50° about the Y-axis, an orientation orthogonal to the tectal layers (B^′′). Note clearly stratified neurite morphology with arbors in SM, SFGS, and SGC layers of tectal neuropil. (C) High magnification views of isolated subvolumes of the SM (C), SFGS (C′), and SGC (C^′′) layer dendrites of neuron in B shown with −40° Y-axis rotation used to calculate retinotopic areas. (D) Workflow for morphological segmentation and measurement of retinotopic areas for PyrN neurite subvolumes. Semi-automated 3D segmentation produces skeletonized tracings used for neurite length and retinotopic area measurements. For direct comparison between raw images and tracings, note that skeletonized tracing was obtained from PyrN shown in (B,C). (E,F) Quantification of retinotopic area and neurite length measurements for the different PyrN neurite subvolumes: SM, SFGS, and SGC. Scale bar: 200 μm in (A), 50 μm in (B), 15 μm in (C), and 20 μm in (D).