Fig. 2. Antisense TSG and chordin MOs block the in vivo activity of TSG and chordin respectively. (A) A stage matched uninjected control embryo. (B,C) Microinjection of 1 ng of Xenopus TSG mRNA per blastomere at the four-cell stage induces head and tail defects in early tailbud stage frog embryos (B), and this phenotype is inhibited by coinjecting 5 ng TSG-MO per blastomere together with the XTSG mRNA (C). (D,E) Similarly, 2.5 pg ChdA mRNA microinjected into the marginal zone of each ventral blastomere at the four-cell stage efficiently induces secondary axes (D) and these are completely blocked by ventral coinjection together with 5 ng/blastomere of ChdA-MO (E). Identical results were obtained for coinjections of ChdB-MO together with ChdB mRNA (data not shown). Coinjection of either XTSG or chordin mRNAs together with a control MO has no effect on the ability of these mRNAs to elicit these phenotypes. In all panels anterior is to the right and dorsal is to the top. 1° and 2° indicate primary and secondary axes.