Fig. 5.

Vascular alterations after intraocular VEGF-A injection. a Morphology of IB4-stained P6 wild-type retinal vessels at 4 h after administration of human VEGF-A165 (0.5 µl at a concentration of 5 μg μl⁻¹). Note blunt appearance of the vessel front after VEGF-A injection but not for vehicle (PBS) control. Scale bar, 200 µm. b Quantitation of sprouts and filopodia at the front of the P6 vessel plexus after injection of VEGF-A165 or vehicle control. Error bars, s.e.m. p-values, Student’s t-test. c PDGFRβ+ (green) pericytes are unaffected by short-term VEGF-A administration, whereas VEGFR2 immunosignals (white) are increased in IB4+ (red) ECs (arrowheads). Images shown correspond to insets in a. Scale bar, 100 µm. d Quantitation of VEGFR2 immunosignals intensity in the peripheral plexus of P6 retinas after injection of VEGF-A165 or vehicle control. Error bars, s.e.m. p-values, Student’s t-test. e Confocal images showing increased Esm1 immunostaining (white) in IB4+ (red) ECs in the peripheral plexus (arrowheads) after VEGF-A injection in P6 pups. Scale bar, 200 µm. f VEGF-A165 injection-mediated increase of Esm1 immunosignals (normalized to IB4+ EC area) in the peripheral capillary plexus but not at the edge of the angiogenic front in comparison to PBS-injected controls at P6. Error bars, s.e.m. p-values, Student’s t-test. NS, not statistically significant. g Short-term VEGF-A165 administration leads to clustering of Erg1+ (green) and IB4+ (red) ECs, as indicated, in thick sprout-like structures of P6 retinas. Panels in the center and on the right (scale bar, 20 µm) show higher magnification of the insets on the left (scale bar, 100 µm). Dashed lines in panels on the right outline IB4+ vessels. h Quantitation of EC density in the leading front vessel and emerging sprouts of the P6 angiogenic front after injection of VEGF-A165 or vehicle control. Error bars, s.e.m. p-values, Student’s t-test