Induction of the dorsal organizer by cell line implantation in MZoep mutants. (A–D) Unimplanted embryos, (E–H) ZE6-1 implanted and (I–L) ZE120-1 implanted MZoep embryos. Whole-mount in situ hybridization for gsc (B, F, G) and flh (C, J, K). (F, G) Expression of gsc in panel E (F) and a longitudinal section of panel F (G). Ectopic gsc was observed in 19 of 20 embryos, ZE6-1. (J, K) Expression of flh in panel I (J) and a longitudinal section of panel J (K). Ectopic flh was observed in 20 of 20 embryos, ZE6-1; 22 of 22 embryos, ZE120-1. Dotted lines in panels G and K indicate the implanted cells. (H, L) Induced secondary axis phenotype in MZoep (30 of 31 embryos, ZE6-1; 29 of 39 embryos, ZE120-1). (A–C, E, F, I, J) Animal pole views. (D, G, H, K, L) Lateral views. (A–C, E–G, I–K) 6 hpf. (D, H, L) 24 hpf. e, eye of secondary axis; o.v., otic vesicle of secondary axis; t, tail of secondary axis. Arrowhead indicates the implanted cells. The large arrows in panels H and L indicate the secondary axis, and small arrows in panels F and J indicate the expression of gsc and flh. Scale bar, 100 μm.
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