Ptf1a cell autonomously biases retinal precursors towards amacrine and horizontal cell fates. Analysis of cell types distribution in stage 40/41 retinas, following Ptf1a or Ptf1a-VP16 lipofection. (A) Percentage of retinal cell types. Values are given as mean +/- s.e.m. p < 0.001 (***) (Student's t test). (B-E) Typical sections of retinas transfected with GFP alone (B, C) or GFP plus Ptf1a-VP16 (D, E), showing the dramatic increase of horizontal cells (arrows). C and E are higher magnifications of the dotted square delineated regions in B and D. Ctrl: control; L: lens; GC: ganglion cells; dAm: displaced amacrine cells; Bip: bipolar cells; Hor: horizontal cells; PH: photoreceptors; Mu: Müller cells. Scale Bar represents 50 μm.