Tam P P, Williams E A, Chan W Y
Embryology Unit, University of Sydney, Australia.
Microsc Res Tech. 1993 Nov 1;26(4):301-28. doi: 10.1002/jemt.1070260405.
Ultrastructural studies and lineage analyses of gastrulating mouse embryos have revealed that different morphogenetic tissue movements are involved in the formation of the three definitive germ layers. Definitive ectoderm is formed by epibolic expansion of the pre-existing progenitor population in the embryonic ectoderm. Formation of the mesoderm and the endoderm is initiated by cellular ingression at the primitive streak. The mesodermal layer is established by cell migration and cell sheet spreading, but the endoderm is formed by replacing the original primitive endodermal population. To this date, genes that are expressed during mouse gastrulation mostly encode cell surface adhesion or signalling molecules, growth factors and their receptors, and putative transcriptional factors. Their precise role during gastrulation remains to be investigated.
对原肠胚形成期小鼠胚胎的超微结构研究和谱系分析表明，不同的形态发生组织运动参与了三个终末胚层的形成。终末外胚层由胚胎外胚层中预先存在的祖细胞群体通过外包扩展形成。中胚层和内胚层的形成始于原条处的细胞内陷。中胚层通过细胞迁移和细胞片层扩展而建立，但内胚层是通过取代原始内胚层群体而形成的。迄今为止，在小鼠原肠胚形成过程中表达的基因大多编码细胞表面粘附或信号分子、生长因子及其受体以及假定的转录因子。它们在原肠胚形成过程中的精确作用仍有待研究。
