Lesseps R J, van Kessel A H, Denucé J M
J Exp Zool. 1975 Aug;193(2):137-46. doi: 10.1002/jez.1401930203.
During epiboly stages the cells (called deep blastomeres) which will form the definitive embryo disperse over the surface of the yolk sphere, only later aggregating and developing an embryonic axis. Five different statistical tests were used to study the pattern formed by the deep blastomeres during epiboly and early dispersed stages. The two most reliable tests, based on the distance from each deep blastomere within a selected area to its nearest neighboring cell, indicate that the distribution pattern changes from regular during epiboly stages to random during dispersed stages 1 and 2. Careful observation and time-lapse microphotography revealed some aspects of how the cells set up the regular pattern. The deep blastomeres exhibit a variety of cell extensions, with which they often contact one another. When two deep blastomeres make contact during epiboly stages, they soon break the contact and move apart; they overlap one another only rarely. Deep blastomeres are frequently located at, and are even elongated along, borders of the overlying flat cells (enveloping layer cells). These two mechanisms, one similar to contact inhibition of cell movement, the other to contact guidance, may contribute to the rather regular spacing of the deep blastomeres as well as to their arrangement in rows during epiboly stages.
在外包期阶段，将形成最终胚胎的细胞（称为深层卵裂球）分散在卵黄球表面，之后才聚集并形成胚胎轴。使用了五种不同的统计测试来研究深层卵裂球在外包期和早期分散阶段形成的模式。基于选定区域内每个深层卵裂球与其最近邻细胞之间的距离，两种最可靠的测试表明，分布模式从外包期的规则模式转变为分散阶段1和2的随机模式。仔细观察和延时显微摄影揭示了细胞如何建立规则模式的一些方面。深层卵裂球表现出多种细胞延伸，它们常借此相互接触。在外包期阶段，当两个深层卵裂球接触时，它们很快就会断开接触并分开；它们很少相互重叠。深层卵裂球经常位于覆盖的扁平细胞（包被层细胞）的边界处，甚至沿其边界伸长。这两种机制，一种类似于细胞运动的接触抑制，另一种类似于接触导向，可能有助于深层卵裂球在外包期阶段形成相当规则的间距以及排列成行。
