Fig. 7. Effect of targeted Ptf1a deletion on the expression of retinogenic factors. (A-J) Sections from E14.5 (A-H) or E18.5 (I,J) wild-type and Ptf1a^Cre/Cre retinas were hybridized with a Ptf1a (A,B), Foxn4 (C,D), Math3 (E,F), Neurod1 (G,H) or Math5 (I,J) riboprobes. Similar levels of Foxn4, Math3 and Neurod1 expression are seen in wild-type and null retinas. Math5 expression is upregulated in the null retina at E18.5. (K-N) Sections from E14.5 (K,L) or E18.5 (M,N) wild-type and null retinas were immunostained with antibodies against Prox1 (K,L) or Lim1 (M,N). Prox1 and Lim1 signals are absent from Ptf1a^Cre/Cre retinas (L,N). (O,P) Cells undergoing apoptosis (green) were TUNEL-labeled in wild-type and null retinas at E18.5. A moderate increase of apoptotic cells is seen in the Ptf1a-null retina. Sections in M-P were weakly counterstained with Yo-Pro-1 (M,N) or DAPI (O,P). Scale bar: 50 µm. Abbreviations: R, retina; L, lens; onbl, outer neuroblastic layer; GCL, ganglion cell layer; IPL, inner plexiform layer.