Fig. 1. Retinal astrocytes do not proliferate indefinitely in GFAP-PDGFA mice. (A-D) Immunohistochemistry on retinal wholemounts from P7 (A,B) and P28 (C,D) animals with an anti-GFAP antibody show increased retinal astrocyte numbers in GFAP-PDGFA transgenic mice (B,D) compared with wild-type mice (A,C). However, retinal astrocytes do not proliferate out of control in transgenic mice (D). (E) Retinal astrocytes in dissociated and overnight-cultured retinae were stained with an anti-GFAP antibody and assessed for BrdU incorporation. Retinal astrocyte proliferation ceases in both wild-type and transgenic mice at about P8. Each data point represents the mean±s.d. from triplicate cultures from four animals (data points labeled with a star are significantly different at a 95% confidence level). (F,G) In situ hybridization of retinal sections from 10-day-old mice reveals that transgene mRNA (human PDGFA) can be readily detected in the astrocyte layer (black arrows) in transgenic animals (F) but not in wild-type animals (G). (H) Combined immunohistochemistry and in situ hybridization on retinal wholemounts shows that retinal astrocytes, identified with an anti-GFAP antibody (white staining), express PDGFRa mRNA (black staining, white arrows) in 14-day-old wild type animals. Scale bars: 200 µm in A-D,F,G; 20 µm in H.