Institute for Biogenesis Research, Department of Anatomy, Biochemistry and Physiology, John A. Burns School of Medicine, University of Hawaii, 651 Ilalo St. Biosciences Building 163 Honolulu, HI 96813, USA.
Mol Reprod Dev. 2009 Nov;76(11):1019-32. doi: 10.1002/mrd.21057.
The first cell lineage specification in mouse embryo development is the formation of trophectoderm (TE) and inner cell mass (ICM) of the blastocyst. This article is to review and discuss the current knowledge on the cellular and molecular mechanisms of this particular event. Several transcription factors have been identified as the critical regulators of the formation or maintenance of the two cell lineages. The establishment of TE manifests as the formation of epithelium, and is dependent on many structural and regulatory components that are commonly found and that function in many epithelial tissues. Distinct epithelial features start to emerge at the late 8-cell stage, but the fates of blastomeres are not fixed as TE or ICM until around 32-cell stage. The location of blastomeres at this stage, that is, external or internal of the embryo, in effect defines the commitment towards the TE or ICM lineage, respectively. Some studies implicate the presence of a developmental bias among blastomeres at 2- or 4-cell stage, although it is unlikely to play a decisive role in the establishment of TE and ICM. The unique mode of cell lineage specification in the mouse embryo is further discussed in comparison with the formation of initial cell lineages, namely the three germ layers, in non-mammalian embryos.
在小鼠胚胎发育过程中,第一个细胞谱系特化是囊胚的滋养外胚层(TE)和内细胞团(ICM)的形成。本文旨在综述和讨论这一特定事件的细胞和分子机制的最新知识。已经确定了几个转录因子作为这两个细胞谱系形成或维持的关键调节因子。TE 的建立表现为上皮的形成,并且依赖于许多在许多上皮组织中普遍存在并发挥作用的结构和调节成分。独特的上皮特征在晚期 8 细胞阶段开始出现,但直到大约 32 细胞阶段,胚胎细胞的命运才固定为 TE 或 ICM。在这个阶段,胚胎的外部或内部位置决定了胚胎细胞向 TE 或 ICM 谱系的特化,分别。尽管在 TE 和 ICM 的建立中不太可能起决定性作用,但一些研究表明,在 2 或 4 细胞阶段,胚胎细胞存在发育偏向。在与非哺乳动物胚胎中初始细胞谱系(即三个胚层)的形成进行比较时,进一步讨论了小鼠胚胎中独特的细胞谱系特化模式。