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. Author manuscript; available in PMC: 2008 Dec 1.
Published in final edited form as: Dev Biol. 2007 Oct 2;312(1):90–102. doi: 10.1016/j.ydbio.2007.09.039

Figure 7.

Figure 7

Ectopic axis induction by vegetal overexpression of an intracellular Wnt activator depends on injection timing. Embryos were injected in a ventral tier D blastomere (D4) at the 32 cell stage with LacZ RNA (5 ng) and -catenin RNA (2 ng). A. Induction of secondary axes by ectopic β-catenin injected in vegetal D4 cells depends on the time elapsed from the start of the D/C tier separation. Incidence of secondary axes induced by β-catenin injected in D4 cells decreases from 75% to 35% when the injection is delayed 15 min after the onset of tier D/C separation. The frequency of ectopic axes induced by C4 injections does not change. Numbers above the columns indicate the total number of injected embryos. B-E. β-galactosidase stain of D4 and C4 injected embryos (stage 36). B. Embryo injected in D4 immediately after the start of tier D/C separation. Anterior and axial stain is present in the secondary axis (arrow). C. Late injection in D4 (15 min after start of cell division). Stain is restricted to endoderm and no secondary axis is induced. D, E. Embryos injected in C4 immediately (D) and 15 min (E) after the onset of cells division. Secondary axes are present and stained in axial and anterior tissues. Arrowheads in C, D and E indicate axial β-Gal stain.