Embryonic expression of a Zic homologue (Ttu-Zic) was examined in the oligochaete annelid Tubifex tubifex. The body plan of T. tubifex is characterized by obvious segmentation in the ectoderm and mesoderm. Ttu-Zic expression is detected in the mesodermal germ band and a subset of micromere descendants. Ttu-Zic is transiently expressed in primary m-blast cells (i.e., founder cells of mesodermal segments) as early as the time of their birth from M teloblasts. During its development, each mesodermal segment experiences two additional phases of Ttu-Zic expression. Ttu-Zic expression in micromere descendants is seen on the anterior surfaces of embryos undergoing teloblastogenesis; subsequently, these cells proliferate to form bilateral clusters, which then become internalized. Finally, clusters of Ttu-Zic-expressing cells are found in the center of the prostomium, corresponding to the cerebral ganglion. The Ttu-Zic expression profile in the early embryogenesis of T. tubifex may be homologous to those of evolutionarily distant animals.

中文翻译：

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寡核苷酸Tubifex tubifex胚胎发育中Annelid Zic的表达模式。

Zic同系物（Ttu-Zic）的胚表达在寡头无壳动物Tubifex tubifex中进行了检查。T.tubifex的身体计划的特征是在外胚层和中胚层中有明显的分割。在中胚层生殖带和一部分微小的子代中检测到Ttu-Zic表达。Ttu-Zic早在M成纤维细胞出生时就在原代m-blast细胞（即中胚层节段的始建细胞）中瞬时表达。在其发展过程中，每个中胚层节段都经历了Ttu-Zic表达的两个附加阶段。在进行成纤维细胞形成的胚胎的前表面可以观察到微粒子代中的Ttu-Zic表达。随后，这些细胞增殖形成双边簇，然后被内化。最后，在pro的中央发现了表达Ttu-Zic的细胞簇，对应于脑神经节。T.tubifex早期胚胎发生过程中的Ttu-Zic表达谱可能与进化距离较远的动物同源。