Fig. 3. Shh inactivation in the peripheral retina is associated with increased RGC development. (A-D) Retinas from wild-type and -Cre;Shh^–/c mice at E17 stained for BrdU and Brn3b. RPC were labelled in vivo with BrdU at E16 and harvested 24 hours later. B and D are high magnification views of the neuroblast layers in A and B, respectively. Arrows in D indicate examples of double-labelled cells. The layer of Brn3b⁺ RGCs is thickened and there is an increase in double-labelled cells in the -Cre;Shh^–/c retina (C,D). (E) Quantification of the number of Brn3b⁺ cells in a 300 µm region in the central and peripheral regions of wild-type and mutant retinas at P0. (F,G) Birthdating analysis in the embryonic -Cre;Shh^–/c retina. RPC were labelled in vivo with BrdU at E13 and the retinas were harvested at P0. The number of Brn3b⁺ cells with intense BrdU-labelling (F) and the proportion of Brn3b⁺ cells among the heavily BrdU-labelled cohort (G) were quantified in 300 µm regions of the central and peripheral retinas in wild-type and mutant mice. *P<0.005. Scale bar: 100 µm in A,C; 50 µm in B,D.