Proliferation defects in dmbx1 morphant embryos. Embryos at 72 hpf were examined for the presence of proliferating cells using immunohistochemistry with antibodies to PCNA, pHH3 or BrdU (30 min survival). Coronal (~15 μm) sections of midbrain (A-D, dorsal to the top) and retina (E-H, dorsal to the top, lens to the left). Arrow in A and B demarcates the proliferative zones of the dorsal and lateral TeO. Arrow in E and G demarcates the CMZ. (I, J) Flow cytometric analysis of retinal cells derived from un-injected or MO1a + MO1b injected embryos at 72 hpf using propidium iodide labeling. N, total number of cells analyzed; G1, gap-1 phase of the cell cycle; S, synthesis phase of the cell cycle; G2, gap-2 phase of the cell cycle; MO, morpholino; mMO, mismatch morpholino; hpf, hours post-fertilization.