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Fig. 9
Zebrafish FGPs are derived from kdrl-expressing endothelium.
(a-c) Lateral view confocal micrographs of a 5 dpf Tg(−9.8actb2:LOXP-DsRED-LOXP-EGFP); Tg(kdrl:Cre) double transgenic ‘switch’ embryo, with ‘unswitched’ DsRed-positive cells (magenta, panels a and b) and ‘switched’ EGFP-positive cells (green, panels a and c) where Kdrl:Cre has successfully excised the LoxP cassette. (d), Lateral view confocal micrograph of a 4 dpf Tg(-9.8actb2:LOXP-DsRED-LOXP-EGFP);Tg(kdrl:Cre) double transgenic embryo injected intravascularly with Qdot705 (red) to highlight all patent vessels. ‘Unswitched’ DsRed is in grey, and ‘switched’ EGFP is in green. (e) Higher magnification image of the yellow boxed area in panel d, showing an optic tectum vessel labeled with Qdot705 (red) surrounded by switched EGFP-positive FGPs (green). (f), Dorsal view confocal micrograph of the brain optic lobes of an adult Tg(−9.8actb2:LOXP-DsRED-LOXP-EGFP); Tg(kdrl:Cre) double transgenic ‘switch’ animal with mosaic expression of EGFP in a subset of FGPs. The white box notes the area shown in panel g. (g), Higher magnification image of the boxed region in panel f, with boxes noting the areas shown at still higher magnification in panels h and i. (h) Higher magnification confocal image showing autofluorescent green vesicles (yellow arrows) in unswitched FGPs. (i) Higher magnification confocal image showing EGFP-positive switched FGPs. Rostral is to the left in panels a-e, and up in panel f-i. Scale bars: 500 µm (a–c), 100 µm (g).