(A) Embryos were injected with mRNA encoding GFP alone (Ctl) or together with antisense morpholino for ADAM13 alone (MO13) or ADAM13 and 19 (2MO). The compounds were injected either in one cell at the 2-cell stage (for graft) or in one dorso-animal cell at the 8–16 cell stage (for targeted injection). The graft procedure was carried out at stage 15 and the embryos were scored for their lack of CNC migration at tailbud stage (26 to 28) for both assays. The pictures show the typical result obtained for each case. The histogram represents the percentage of embryos with no CNC migration normalized to embryos injected with GFP alone and corresponds to the mean of seven (targeted injection) and at least six (graft) independent experiments. The number of embryos scored is as follows. For grafts: Ctl; n=42, MO13; n=25, 2MO; n=61. For targeted injection: Ctl; n=248, MO13; n=258, 2MO; n=281. While 2MO inhibits CNC migration at similar levels for both the grafts and the targeted injection assays, MO13 alone is 5 times more efficient at inhibiting CNC migration in the targeted injection assay than the graft assay. (B) Embryos were injected in one cell at the 2-cell stage with either GFP (Ctl donor), GFP and MO13 (MO13 donor) or RFP and MO13 (MO13 recipient). At stage 15, three types of grafts were performed: 1-GFP expressing CNC were grafted into non-injected embryos (Ctl->NI), 2- GFP+ MO13 injected CNC were grafted into non-injected embryos (MO13->NI), 3- GFP+MO13 injected CNC were grafted into embryos injected with RFP+MO13 (MO13->MO13). The pictures show the typical result obtained for each case. The histogram represents the percentage of embryos with no CNC migration normalized to embryos injected with GFP alone and corresponds to the mean of three independent experiments, representing the scoring of 20 embryos for each case. Results show that morphant CNC display a statistically identical level of migration inhibition whether they are grafted into a wild type embryo or a morphant embryo. The error bar represents standard deviation from the mean. *=Statistically different from controls (p<0.05). Arrowheads point to the segments of the CNC. m: mandibular, h: hyoid, b1 and b2: branchial.