Fig. 4. Ephrin-Ad provides the notochord-suppressing signals from
anterior-animal cells. Expression of Ci-Bra (A-D)
and Ci-ETR (E-H) at the 64- and 110-cell stages,
respectively, following the treatments indicated above the panels. The average
number of cells positive for each marker gene is indicated in each panel,
together with the total number of samples analysed. Embryos in A,C and D are
slightly tilted in order to place the notochord and neural precursors in the
same focal plane. Schematics in B and F represent vegetal-pole views of the
64- and 110-cell-stage embryos, respectively, with notochord in orange and
neural cells in yellow. Black dots mark cells positive for Ci-Bra (in
B) and Ci-ETR (in F) in the control embryo. dnEph3-RNA injection gave
similar results to ephrin-Ad-MO injection (7.2 cells for Ci-Bra,
n=34; 1.2 cells for Ci-ETR, n=22).