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. 2017 Oct;58(12):5421–5433. doi: 10.1167/iovs.17-22442

Figure 6.

Figure 6

Prdm16 marks large diameter vessels inside and outside the eye. Sections and retinal flatmounts stained with Prdm16 (green) and vascular markers. (A) At P12, Prdm16 marks the RPE and a subset of ganglion cells (arrowheads). Elongated Prdm16 nuclei are seen in the choroid (ch) (blue, white arrows, insets); the retina (purple arrows, insets); and near extraocular muscles (*-arrow). These nuclei form tubular structures indicative of blood vessels. No Prdm16+ capillaries are seen within the retina and only a small subset of the choroidal vessels are labeled. (B, C) Horizontal sections of an E15.5 embryo stained for Erg1 (red), which marks vascular endothelial cell nuclei. In the developing eye (B), Prdm16 labels the RPE and a small subset of the choroidal vessels (arrows, inset). The fetal vascular networks (VHP, vasa hyaloidia propria; TVL, tunica vasculosa lentis) in the vitreous (arrowheads) did not coexpress Prdm16. Caudally, (C) large diameter vessels adjacent to the brain express Prdm16 and Erg1 (arrows, insets). Prdm16+ neural cells (arrowheads) and chondrocytes (Chon) are evident. (D–O) Adult retinal flatmounts. (D–G) Flatmount stained with GsiB4 lectin (red) to mark all blood vessels. Only a subset of large diameter vessels coexpress Prdm16 (arrows). Prdm16+ ganglion cells are marked with arrowheads. ON, optic nerve. (H, I) Flatmounts stained with Erg1 (red). Within positive vessels, essentially all Erg1+ endothelial cells coexpress Prdm16 (arrows, insets). (J, K) High power view of flatmounts stained with Erg1 (red) and Pdgfrβ (gray) to mark mural cell membrane. A subset of mural cells coexpresses Pdgfrβ and Prdm16 (arrows, insets). Arrowheads mark Prdm16+ endothelial cells. (L–O) Staining with GsiB4 lectin (red) and α-smooth muscle actin (αSMA; gray) to mark all vessels and arteries/arterioles (a), respectively. Prdm16 staining correlated tightly with αSMA staining (arrows, insets). Capillaries (c) did not express Prdm16 or αSMA. Some Prdm16+ cells are strongly αSMA+ (blue arrows, insets), suggesting that they are vascular smooth muscle cells. Arrowheads mark Prdm16+ ganglion cells. Scale bar: 250 μm for (A); 100 μm for (B) through (E), (H), (I), (L) through (O); and 50 μm for (F), (G), (J), (K). Scale bars for insets are 50 μm for (A); 25 μm for (B), (C), (H) (I), (L) through (O); and 10 μm for (J) and (K) and the blue insets in (L) through (O).