Optic cup development in whole mouse embryo culture. A-S' are serial transverse sections through the developing optic vesicle and optic cup, ordered with dorsal (D) sections uppermost. A-H, I-M, and N-S show Tbx5 expression (in blue). (A-C) E10.5 optic vesicle (not cultured). (D-H) Post-culture early optic cup. Compare with A-C for pre-culture stage of development and to D'-H' for a stage matched non-cultured optic cup. Invagination to form an optic cup with a thick neural retina (NR) surrounded by a thin layer of presumptive retinal pigmented epithelium (RPE), and formation of a lens vesicle (L) occur normally during culture. (I-M) Post-culture optic cup implanted with a control bead, showing normal eye morphology and gene expression. (N-S) Post-culture late optic cup. Compare with D'-H' for the approximate pre-culture stage of development and with N'-S' for the non-cultured stage matched equivalent. Growth of the NR, pigmentation of the RPE, and apposition of the optic fissure walls (indicated by arrows in S and S') proceed normally during culture. Scale bars: 0.1 mm. Abbreviations: D, dorsal; L, lens vesicle; NR, neural retina; P-NR; presumptive neural retina; OF, optic fissure; OS, optic stalk; RPE, retinal pigmented epithelium; P-RPE, presumptive RPE; ss, somite stage; V, ventral.