Figure 3.

P1 and P3 flatmount retinas labeled with anti-GFAP (red) and GS isolectin (green). At P1, removal of the vitreous revealed an apron of vessels around the optic nerve head behind an astrocyte template in both the WT (A) and the Lama1^nmf223 retinas (B). A similar image was observed in the Lama1^nmf223 retina at P3 when the vitreous was removed (C). The WT vasculature (arrow) extended into the mid retina at P3 (D). Higher magnification more clearly demonstrated the endothelial filopodia following the GFAP-positive astrocyte template in the WT retina (E). When imaged with the vitreous intact, it is clear that astrocytes ensheath the retinal vessels but not the hyaloid (arrow) in the WT (F). By contrast, imaging of the Lama1^nmf223 retina with the vitreous still intact, demonstrated the migration of astrocytes into the vitreous (G). The hyaloid vessels are proliferating at this stage rather than regressing. Removal of the vitreous demonstrated that very few astrocytes (arrowhead) remained in the retina beyond the peripapillary region (H). Astrocytes could be seen ensheathing the vitreal blood vessels (arrows) in the Lama1^nmf223 retinas (I). A capillary network had started to form in the vitreous of the Lama1^nmf223 mutants (G). Scale bars indicate A- D: 100 μm; D-I: 50 μm).