Department of Molecular Biomedical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina 27606, USA.
Dev Dyn. 2009 Dec;238(12):3111-25. doi: 10.1002/dvdy.22157.
During digestive organogenesis, the primitive gut tube (PGT) undergoes dramatic elongation and forms a lumen lined by a single-layer of epithelium. In Xenopus, endoderm cells in the core of the PGT rearrange during gut elongation, but the morphogenetic mechanisms controlling their reorganization are undetermined. Here, we define the dynamic changes in endoderm cell shape, polarity, and tissue architecture that underlie Xenopus gut morphogenesis. Gut endoderm cells intercalate radially, between their anterior and posterior neighbors, transforming the nearly solid endoderm core into a single layer of epithelium while concomitantly eliciting "radially convergent" extension within the gut walls. Inhibition of Rho/ROCK/Myosin II activity prevents endoderm rearrangements and consequently perturbs both gut elongation and digestive epithelial morphogenesis. Our results suggest that the cellular and molecular events driving tissue elongation in the PGT are mechanistically analogous to those that function during gastrulation, but occur within a novel cylindrical geometry to generate an epithelial-lined tube.
在消化器官发生过程中，原始肠道管（PGT）经历剧烈的伸长，并形成由单层上皮衬里的管腔。在非洲爪蟾中，PGT 核心中的内胚层细胞在肠道伸长过程中重新排列，但控制其重组的形态发生机制尚不清楚。在这里，我们定义了构成非洲爪蟾肠道形态发生基础的内胚层细胞形状、极性和组织架构的动态变化。肠道内胚层细胞在它们的前、后邻居之间进行放射状的插入，将几乎实心的内胚层核心转变为单层上皮，同时在肠道壁内引起“放射状会聚”延伸。抑制 Rho/ROCK/肌球蛋白 II 活性可防止内胚层重排，从而扰乱肠道伸长和消化上皮形态发生。我们的结果表明，驱动 PGT 组织伸长的细胞和分子事件在机制上类似于那些在原肠胚形成过程中起作用的事件，但发生在一种新的圆柱形几何形状中，以生成内衬上皮的管腔。
