Loss of retinal differentiation and laminar structure in GDF6 depleted embryos. Histology of stage 41 embryos with small eyes following GDF6 MO injection (20 ng) compared with normal stage matched controls. DAPI staining of small eye (B, D, F, and H) compared with normal eye (A, C, E, and G) showing small eyes have a lack of laminar structure and appear disorganized. (A, B) Photoreceptors (p) are not stained in B compared with XAP-1 staining in A. (B) Cell bodies are visibly extending outward (white arrow) but do not stain for XAP-1. Red staining next to the lens is non-specific staining also detected in a proportion of negative controls. (C, D) 40.2D6 detects ganglion (g) and amacrine (a) cells within the normal retina, but these cells are not detected in the small eye. Photoreceptors are visible due to autofluorescence at increased exposure. (E, F) Small disorganized eyes show a loss of immunostaining for the cytoplasmic domain of NCAM (n). (G, H) Mitotic cells (m) detected using anti-phosphorylated-histoneH3 are few and found mainly in the ciliary marginal zone in normal stage 41 embryos. The small eye shows a few mitotic cells near the RPE layer.