Cross sections taken from cryopreserved eyes with GA were labeled with vimentin, GFAP, and peanut agglutin (PNA) to verify that the gliotic lesions coincided with RPE and photoreceptor loss. In the nonatrophic region, where PNA
+ photoreceptor segments were visible, vimentin labeled the entire Müller cell length (
Figs. 7A,
7B). Müller cell apical processes and photoreceptor inner segments created a clearly defined ELM. Glial fibrillary acidic protein was primarily confined to astrocytes in the nonatrophic area (
Figs. 7A,
7C). At the border of the atrophic area, photoreceptors appeared to have lost their polarity and segments extended horizontally instead of vertically (
Figs. 7A,
7B,
7D,
7E). Müller cell processes in this area were GFAP
+ and had a more horizontal orientation (
Figs. 7A–C, 7D, 7E). A thick band of GFAP
+/vimentin
+ glial processes with some DAPI
+ nuclei were observed posterior to these segments. This band ended abruptly where photoreceptor segments regain their linear morphology. In the atrophic area, GFAP
+/vimentin
+ processes occupy the remnant subretinal space in place of photoreceptor segments (
Figs. 7A–H). Müller cell processes within the retina anterior to this atrophic area were GFAP
+ and disorganized. While a few DAPI
+ nuclei were observed in the ONL anterior to the glial membrane, these appeared to be vimentin
+ cells. DAPI staining was also observed within the glial membrane. Focal areas with PNA labeling were observed anterior to the membrane. Müller cells anterior to the membrane were not as linear and appeared disorganized compared with the nonatrophic area. The subretinal location of the membrane was confirmed by staining an adjacent section with hematoxylin and eosin (
Fig. 7I). Retinal pigment epithelial cells are observed adjacent to the atrophy but no pigmented cells were observed within the subretinal membrane. This image also demonstrated that glia abut Bruch's membrane and, in one area, appeared to merge with Bruch's membrane. An adjacent section was stained for vimentin, CD34 (blood vessel marker), and PNA (
Fig. 8). As suggested by flatmount analysis, choriocapillaris loss was observed in the atrophic area and coincided with the subretinal vimentin
+ membrane.