GFAP and retinitis pigmentosa 1: The overall process of glial activation and GFAP upregulation typical of RP (Marc et al., 2003; Gargini et al., 2007; Jones et al., 2016) appears limited in the rd9 phenotype, with mild activation of Muller cell processes and presence of infiltrating and/or migrating microglia/macrophages in the outer retina and mostly at the subretinal space.