Cumulative BrdU labelling reveals an increase in the morphant progenitor cell cycle in the 72 hpf retina. (A-F) Immunolabelled coronal sections (dorsal to the top, lens to the left) from embryos repeatedly injected with BrdU (red) after different survival times (indicated on the left). Sections were counter-stained with DAPI (blue). (G, H) Regression analyses from cumulative labelling data. MO, morpholino; hpf, hours post-fertilization, hr, hours.