Figure 3. Laser scanning confocal images illustrating immunoreactivity for synemin, glial fibrillary acidic protein, and the isolectin B4 labeling in cryosections of control retina and following 30 days of injury. A: In control tissue, sparse synemin immunoreactivity (red) is present in astrocytes of the nerve fiber layer (NFL; arrows), as well as in cells along the inner border of outer plexiform layer (OPL, asterisk), perhaps representing the labeling of horizontal cells. B-G: After injury, anti-synemin labeling appears as vertical streaks across the retina representing the processes of Müller cells (B, arrows) as well as more intense labeling of astrocytes extending processes laterally in the NFL (B). The triple-labeled control retina shows the presence of anti-glial fibrillary acidic protein (GFAP, green) labeled astrocytes in the NFL, and an isolectin B4-positive blood vessel (blue, arrow) coursing across the inner retina (C). Following long-term injury, many Müller cells express synemin from the inner retina to the outer limiting membrane (OLM, D-G), although this population shows little overlap with radial processes expressing GFAP at this time. Anti-synemin labeling also increased in astrocytes after injury, now extending into the outer retina but still associated with retinal blood vessels (D-G, arrows). Scale bars represent 20 μm. ONL represents outer nuclear layer; OPL represents outer plexiform layer.