Wilson P A, Oster G, Keller R
Department of Zoology, University of California, Berkeley 94720.
Development. 1989 Jan;105(1):155-66. doi: 10.1242/dev.105.1.155.
We make use of a novel system of explant culture and high resolution video-film recording to analyse for the first time the cell behaviour underlying convergent extension and segmentation in the somitic mesoderm of Xenopus. We find that a sequence of activities sweeps through the somitic mesoderm from anterior to posterior during gastrulation and neurulation, beginning with radial cell intercalation or thinning, continuing with mediolateral intercalation and cell elongation, and culminating in segmentation and somite rotation. Radial intercalation at the posterior tip lengthens the tissue, while mediolateral intercalation farther anterior converges it toward the midline. This extension of the somitic mesoderm helps to elongate the dorsal side of intact neurulae. By separating tissues, we demonstrate that cell rearrangement is independent of the notochord, but radial intercalation - and thus the bulk of extension - requires the presence of an epithelium, either endodermal or ectodermal. Segmentation, on the other hand, can proceed in somitic mesoderm isolated at the end of gastrulation. Finally, we discuss the relationship between cell rearrangement and segmentation.
我们利用一种全新的外植体培养系统和高分辨率视频记录技术，首次对非洲爪蟾体节中胚层内趋同延伸和分节过程背后的细胞行为进行分析。我们发现，在原肠胚形成和神经胚形成期间，一系列活动从前向后席卷体节中胚层，起始于放射状细胞插入或变薄，接着是中外侧细胞插入和细胞伸长，最终以分节和体节旋转告终。后尖端的放射状插入使组织变长，而更靠前的中外侧插入则使组织向中线汇聚。体节中胚层的这种延伸有助于拉长完整神经胚的背侧。通过分离组织，我们证明细胞重排独立于脊索，但放射状插入——以及因此大部分的延伸——需要内胚层或外胚层上皮的存在。另一方面，分节可以在原肠胚形成末期分离出的体节中胚层中进行。最后，我们讨论了细胞重排与分节之间的关系。
