Figure 4

Amacrine cell genesis is elevated postnatally in Zac1^+m/- retinae. (a-d) E18.5→4DIV wild-type (a,a',c,c') and Zac1^+m/- (b,b',d,d') explants co-labeled with BrdU (red, S-phase) and Pax6 (green; amacrine cells (a,a',b,b') or Math3 (green; amacrine and bipolar precursors in INL (c,c',d,d'). (e,f) E18.5→4DIV explants labeled with Pax6 alone (red). (g,g',h,h') Birthdating of E18.5→8DIV wild-type (g,g') and Zac1^+m/- (h,h') retinal explants exposed to BrdU (green) at 2DIV and co-labeled with anti-Pax6 (red). BrdU/Pax6 double⁺ cells are marked by arrowheads in (g',h'), which are high magnification images of boxed areas in (g,h), respectively. (i) Percentage of BrdU/Pax6 double⁺ nuclei (amacrine cells born at time of BrdU exposure) in wild-type (black bar; BrdU at 1DIV: 562 BrdU/Pax6 double⁺/2,385 Pax6⁺; 2DIV: 527 BrdU/Pax6 double⁺/6,022 Pax6⁺; 4DIV: 77 BrdU/Pax6 double⁺/1,496 Pax6⁺; all counts in 8DIV explants) and Zac1^+m/- explants without an ECL (grey bar; BrdU at 1DIV: 1,307 BrdU/Pax6 double⁺/4,084 Pax6⁺; 2DIV: 527 BrdU/Pax6 double⁺/4,926 Pax6⁺; 4DIV: 75 BrdU/Pax6 double⁺/1,660 Pax6⁺) and Zac1^+m/-+ECL explants (white bar; BrdU at 1DIV: 2,126 BrdU/Pax6 double⁺/6,107 Pax6⁺; 2DIV: 883 BrdU/Pax6 double⁺/4,386 Pax6⁺; 4DIV: 335 BrdU/Pax6 double⁺/3,587 Pax6⁺). (j) Model of amacrine cell genesis in wild-type (red line) versus Zac1^+m/-+ECL (blue line) retinae.