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Fig. 7. Xenopus ectodermal explants and ventralized embryos do not express neural border markers. Uninjected control X. laevis embryos, β-catenin morphants, and animal caps cut from blastula stage uninjected or noggin-injected embryos were cultured to stage 20 and assayed for expression of the neural border markers pax3, hairy2a, and zic2, and the neural crest marker slug. Expression of these genes was not detected in animal caps or β-catenin morphants (of β-catenin morphants, 0% expressed hairy2a (n = 14), pax3 (n = 15), and zic2 (n = 14), while 6% expressed slug weakly (n = 16). All four genes had some expression in animal caps cut from embryos injected with 1 pg of noggin mRNA (63% for hairy2a, n = 8; 50% for pax3, n = 10; 79% for slug, n = 14; and 67% for zic2, n = 9) . The epidermal marker cytokeratin is strongly expressed in β-catenin morphants but excluded from the blastopore. Cytokeratin is strongly expressed in both injected and uninjected animal caps, but was somewhat weaker in noggin-injected animal caps. Embryos are shown in dorsal views with anterior to the left. |
