Fig. 7. Lowering FGF8 levels causes a reduction in placode formation and neural differentiation. (A-E) X. laevis embryos displayed dorsoanteriorly. Embryos were cultured with XlMOF8 (10 ng) or MOSAF8a (60 ng) until the neural tube stage 20; lineage tracer (pink). (B,C) XlMOF8 caused sox2 mispatterning (40/42), so did MOSAF8a but to a lesser degree (20/22). (E) MOSAF8a resulted in a slight expansion of the rx1 domain toward the posterior (16/20). (F-M) The effect of FGF8 reduction on early neuronal differentiation in X. tropicalis. XtMOF8 (8 ng), MOSDF8 (17 ng) and MOSAF8a (16 ng) were injected into one cell at the two-cell stage; injected side is oriented downwards. (F,H,J,L) Embryos were cultured until neurula stages; injected embryos demonstrate an early strong reduction in neuronal differentiation [XtMOF8 (20/20), MOSDF8 (9/9), MOSAF8a (16/16)]. (G,I,K,M) Embryos were cultured until the early tadpole stage; injected embryos demonstrate posterior truncations and continued reduction in differentiated neurons