GFAP and retinal degeneration: In the RHOP23H transgenic rat, the number of astrocytes is higher than in the age-matched wild type (WT) control due to the retinal degeneration [33], and the GFAP immunoreactivity extends from the GCL through the ONL, indicating activation of Müller cells and retinal gliosis [32], as reproduced in our untreated RHOP23H explants (Figure 7, vehicle).