Viebahn C
Institute of Anatomy, University of Bonn, Germany.
Acta Anat (Basel). 1995;154(1):79-97. doi: 10.1159/000147753.
The earliest example of epithelio-mesenchymal transformation during embryonic development is the generation of the third germ layer, the mesoderm, from the epiblast (or primitive ectoderm), which marks the beginning of gastrulation. Although it has been regarded as most likely that the principles of this transformation in invertebrates and lower vertebrates also apply to amniotes, morphological and molecular details of mesoderm formation in birds and, in particular, in mammals, which may support this assumption, have only recently been clarified. This chapter thus brings together the light- and electron-microscopical morphology of epithelio-mesenchymal transformation during initial mesoderm formation in the mammalian embryo. Cellular differentiation during this process with regard to the cytoskeleton, cell adhesion molecules and the extracellular matrix are also covered as are cell kinetic studies and the candidate growth factors and genes most likely to be involved in the regulation of mesoderm formation in mammals. Finally, a model is presented which summarizes these morphological and molecular changes and which links the promoting and inhibiting influences of regulatory factors to some of the changes observed during epithelio-mesenchymal transformation.
胚胎发育过程中上皮-间充质转化的最早例子是上胚层（或原始外胚层）产生第三胚层——中胚层，这标志着原肠胚形成的开始。尽管人们一直认为无脊椎动物和低等脊椎动物中这种转化的原理也适用于羊膜动物，但鸟类尤其是哺乳动物中中胚层形成的形态学和分子细节（这些细节可能支持这一假设）直到最近才得以阐明。因此，本章汇集了哺乳动物胚胎初始中胚层形成过程中上皮-间充质转化的光学显微镜和电子显微镜形态学。还涵盖了此过程中关于细胞骨架、细胞黏附分子和细胞外基质的细胞分化，以及细胞动力学研究和最有可能参与调节哺乳动物中胚层形成的候选生长因子和基因。最后，提出了一个模型，该模型总结了这些形态学和分子变化，并将调节因子的促进和抑制作用与上皮-间充质转化过程中观察到的一些变化联系起来。
