Overexpressing Egfl7 in the postnatal retina results in arterial and venous defects and an increase in vascular coverage. (A) Quantitative RT-PCR analysis of Egfl7 and miR126 expression in P5 retinas isolated from wild-type (□, n = 4) and transgenic (■, n = 6) mice. Egfl7 expression is normalized to endothelial cell number using CD31 expression. *P < .03. (B) Wild-type (i-iii) and transgenic (iv-vi) retinal vasculature at P5, stained with fluorescein isothiocyanate–labeled BS-1 lectin. Red dots represent branching at the distal ends of the vessel; white dots, branching along the vessel length; arrowheads, tortuous veins; and arrows, venous knot-like structures. Original magnification 10×/0.4NA, water objective (i,iv), 20×/0.7NA, water objective (ii,v), and 63×/1.2NA, (iii,vi). (C) Vascular coverage in wild-type (i) and transgenic (ii) retinas at P5. Boxed regions correspond to areas where coverage was measured. (iii) Average vascular coverage at the peripheral and central plexus for wild-type (□, n = 8) and transgenic (■, n = 14) retinas. *P < .05. (iv) CD31 mRNA expression in wild-type (□, n = 4) and transgenic (■, n = 6) retinas. Filopodia in wild-type (v) and transgenic (vi) retinas. (vii) Average filopodia number per 100-μM vessel length for wild-type (□, n = 5) and transgenic (■, n = 9) retinas. *P < .05. Values for vascular coverage and filopodia number are represented as fold difference relative to wild-type. Original magnification 20× (i,ii) and 40×/1.3NA, water objective (v,vi). (D) Summary of phenotypes observed in Egfl7 transgenic retinal vasculature at P5. Images of the retinal vasculature were captured on the TCS AOBS SP2 microscope (Leica), and filopodia was imaged using the LSM 5Live DuoScan microscope (Carl Zeiss).