Figure 1. Postnatal angiogenesis is significantly reduced in Pdgfb^icre/+ dnRAR403^fl/fl mice.

Postnatal (P) day 1–3 mice were injected with tamoxifen and analyzed at P6. Pdgfb^icre/+ recombination and expression of dnRAR403 was determined by immunostaining for the Myc-tag present in the dnRAR403 protein. Myc-tag expression was only present in Pdgfb^icre/+ dnRAR403^fl/fl and not a Cre-littermate control and Myc signal overlapped with lectin-labeled vasculature (A). Compared to wildtype (WT), Pdgfb^icre/+, and dnRAR403^fl/fl mice, Pdgfb^icre/+ dnRAR403^fl/fl retinas (B; DAPI, blue; collagen 4, magenta; PECAM, white) had significantly reduced vascular expansion (C). Analysis of the primary plexus blood vessel area revealed that compared to controls, Pdgfb^icre/+ dnRAR403^fl/fl retinas had significantly less blood vessel area (D). Analysis of the presence of collagen-4 (Collagen-4) sleeves (E, magenta) revealed that compared to controls, Pdgfbicre/+ dnRAR403^fl/fl retinas have significantly decreased Collagen-4 sleeves at P6 (F). Endothelial cells were stained with claudin-5 (G, white) and the outside of each endothelial cell was outlined (yellow dashes) to quantify endothelial cell area. There was no significant difference in endothelial cell volume between dnRAR403^fl/fl controls and Pdgfb^icre/+ dnRAR403^fl/fl mutants (H). (p <0.05, *; p<0.01, **; p<0.001, ***).