Fig. 3. Increased apoptosis in sympathetic neurons in Egr3^-/- mice. (A) No significant differences in apoptosis were observed until P0, at which point apoptosis in Egr3^-/- SCG was nearly double that of wild type (results of Casp3⁺ cells from two to six ganglia of each genotype and developmental time point, ^*P<0.01, Student's t-test). Representative images of ganglia of wild-type (right, top) and Egr3^-/- mice (right, bottom) (results from cultures performed in triplicate). Scale bars: 40 µm. (B) Cellular proliferation (BrdU⁺ cells) was not altered in the SCG between wild-type and Egr3^-/- mice at P0. (C) There was no autonomous defect in NGF-dependent survival of Egr3^-/- SCG neurons in vitro. There was a highly significant correlation between neuron survival and NGF concentration, but no significant difference in the amount of survival between wild-type and Egr3^-/- neurons at any NGF concentration tested. Representative images of sympathetic neurons stained with Hoechst/DAPI (right, top) and Casp3 (right, bottom) (results from cultures performed in triplicate).