Immunohistochemistry was carried out as previously described33 (link). The primary antibodies used were rabbit anti-GFP (1:1000; Invitrogen) and mouse nc82 (1:50, DSHB). The secondary antibodies used were goat anti-rabbit Alexa-488 and goat anti-mouse Alexa-568 (Invitrogen). Images are maximum intensity projections of confocal z-stacks acquired using a Leica SP5 II confocal microscope with 25x water immersion objective.