GDNF and retinal degeneration: Many of the factors involved in this “dialogue” have been identified; MGC release several molecules, such as FGF, GDNF, DHA, and LIF, that rescue PHRs in different models of retinal degeneration (Faktorovich et al., 1990, 1992; LaVail et al., 1992, 1998; Rotstein et al., 1996; Cayouette et al., 1998; Chong et al., 1999; Frasson et al., 1999; Harada et al., 2002; Miranda et al., 2009; German et al., 2013).