Xenbase Image ID: 45420

Fig. 11. XPOX2 expression in progeny cells of the dorsal-vegetal blastomeres. (A) Diagram illustrating the injection site of the cell-lineage marker, biotin-dextran (pale blue), into an individual dorsal-vegetal blastomere of an eight-cell stage Xenopus embryo. The animal and vegetal poles, and the dorsal-ventral axis, are indicated. The embryos were allowed to develop until stages 22–23, whereupon they were fixed and assayed for XPOX2 mRNA expression, and stained to reveal the daughter cells of the injected blastomere. In 27 correctly targeted embryos, when viewed from the ventral side (Lane and Smith, 1999), we observed two subtly different juxtapositions of myeloid gene expression and the posterior boundary of the dorsal-vegetal progeny cells, which are shown (B–D,E–G). Nevertheless, with both observed configurations, the myeloid cells are wholly derived from the dorsal-vegetal blastomeres. The converse cell-fate mapping experiment of ventral-vegetal blastomere cell-lineage injection never resulted in ventrally derived mesoderm present within the domain of myeloid cells at stage 22 (data not shown). (B,E) Ventral views of the site of myeloid cell development for such representative tailbud embryos showing the progeny cells of the dorsal-vegetal blastomere (pale blue) and XPOX2 expression (magenta). The stage 22 embryo (B) has left-sided lineage staining while the stage 23 embryo (E) has right-sided lineage staining. Black lines indicate the positions of the transverse sections illustrated (C,D,F,G). Red arrows (C,F,G) on the sections mark mesodermal regions of coincident cell-lineage staining and XPOX2 expression, which appears a dark blue colour. Sections (10 μm) are numbered (top right of each panel) commencing from the anterior limit of the XPOX2 expression domain. Pigmented-wildtype embryos were used for this experiment. A, anterior; P, posterior; Ect, ectoderm; Mes, mesoderm; End, endoderm. Image published in: Smith SJ et al. (2002) Copyright © 2002. Image reproduced with permission of the Publisher, Elsevier B. V. Gene Synonyms Species Stage(s) Tissue mpo.L mpo-A, myeloperoxidase, pmr-1, pmr1, pox2, xpox2 X. laevis Throughout NF stage 22 to NF stage 23 myeloid cell anterior ventral blood island ventral mesoderm Image source: Published Larger Image Printer Friendly View

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