Hogan B L, Tilly R
J Embryol Exp Morphol. 1981 Apr;62:379-94.
Morphological and biochemical evidence is presented that the visceral extraembryonic endoderm of the 6.5-day mouse embryo will differentiate into parietal endoderm when cultured in contact with extraembryonic ectoderm undergoing transition into trophoblast giant cells. Egg cylinders from 6.5-day embryos were dissected into embryonic and extraembryonic halves and cultured in suspension in vitro for up to 7 days. After 4 days, the endoderm cells of the extraembryonic fragments morphologically resemble parietal endoderm, are associated with a thick basement membrane and synthesize large amounts of the matrix proteins laminin and Type IV procollagen. A similar transition in phenotype is not seen in the endoderm of embryonic fragments, nor in visceral extraembryonic endoderm cells cultured in isolation. In another series of experiments, complete egg cylinders were dissected free of visceral endoderm overlying the extraembryonic ectoderm and then cultured in vitro. The visceral endoderm cells which recolonize the surface of the extraembryonic ectoderm develop a parietal endoderm phenotype and lay down a thick basement membrane. These results suggest that the differentiation of the extraembryonic endoderm of the early mouse embryo into visceral and parietal phenotypes can be influenced by local cell-cell or cell-substrate interactions, and is not determined solely by cell lineage.
有形态学和生化证据表明，6.5天龄小鼠胚胎的脏壁外胚层内胚层在与正转变为滋养层巨细胞的外胚层接触培养时会分化为壁层内胚层。将6.5天龄胚胎的卵圆柱解剖为胚胎和外胚层两部分，并在体外悬浮培养长达7天。4天后，外胚层片段的内胚层细胞在形态上类似于壁层内胚层，与一层厚的基底膜相关联，并合成大量的基质蛋白层粘连蛋白和IV型前胶原。在胚胎片段的内胚层中，以及在单独培养的脏壁外胚层内胚层细胞中，均未观察到类似的表型转变。在另一系列实验中，将完整的卵圆柱从覆盖在外胚层上的脏壁内胚层分离出来，然后进行体外培养。重新定殖在外胚层表面的脏壁内胚层细胞发育出壁层内胚层表型，并形成一层厚的基底膜。这些结果表明，早期小鼠胚胎的外胚层内胚层向脏壁和壁层表型的分化可能受局部细胞-细胞或细胞-基质相互作用的影响，而不仅仅由细胞谱系决定。
