Turner A, Snape A M, Wylie C C, Heasman J
Department of Zoology, University of Cambridge, England.
J Exp Zool. 1989 Aug;251(2):245-52. doi: 10.1002/jez.1402510212.
Regional differences in cell recognition properties along the animal-vegetal axis of Xenopus laevis embryos were investigated by using an in vitro cell sorting assay. Dissociated cells were obtained from defined regions of blastula- and early gastrula-stage embryos. Binary combinations of cells from different regions, or from the same region at different ages, were aggregated in stationary culture. Labelling of one population in each pair with a cell-autonomous dye allowed the degree of sorting out in the resulting aggregates to be scored. In combinations of cells from animal caps (prospective ectoderm) and vegetal masses (prospective endoderm), sorting was detectable at the equivalent of late blastula stage and increased with developmental age to the gastrula stage. In addition, cells from the same region but different stages sorted from each other, indicating temporal changes in regional identity. Marginal cells (prospective mesoderm) sorted strongly from vegetal cells but only weakly from animal cells. These results indicate the presence of regional identity in the form of specific recognition properties in cells of the Xenopus blastula. We suggest that these properties act to establish and maintain coherent cell populations, corresponding to the primary germ layers, prior to gastrulation. These results account for the gradual restriction in developmental capacity of blastomeres seen previously in single-cell transplantation experiments from this laboratory.
通过使用体外细胞分选试验，研究了非洲爪蟾胚胎动物 - 植物轴上细胞识别特性的区域差异。从囊胚期和早期原肠胚期胚胎的特定区域获得解离细胞。来自不同区域或不同年龄同一区域的细胞的二元组合在静止培养中聚集。用细胞自主染料对每对中的一个群体进行标记，使得能够对所得聚集体中的分选程度进行评分。在动物帽（预期外胚层）和植物团块（预期内胚层）的细胞组合中，在相当于囊胚晚期阶段可检测到分选，并且随着发育年龄增加到原肠胚期而增加。此外，来自同一区域但不同阶段的细胞相互分选，表明区域特征存在时间变化。边缘细胞（预期中胚层）与植物细胞强烈分选，但与动物细胞仅微弱分选。这些结果表明非洲爪蟾囊胚细胞中存在以特定识别特性形式的区域特征。我们认为这些特性在原肠胚形成之前起到建立和维持与主要胚层相对应的连贯细胞群体的作用。这些结果解释了先前在本实验室的单细胞移植实验中所观察到的卵裂球发育能力的逐渐限制。
