Yamamoto Yoshiyuki, Suzuki Akio S
Natural Environmental Science, Department of Environmental Science, Graduate School of Science and Technology, Kumamoto University, Kumamoto City, Japan.
Rouxs Arch Dev Biol. 1994 Oct;204(1):11-19. doi: 10.1007/BF00189063.
The isolated upper marginal zone from the initial stage of Cynops gastrulation is not yet determined to form the dorsal axis mesoderm: notochord and muscle. In this experiment, we will indicate where the dorsal mesoderm-inducing activity is localized in the very early gastrula, and what is an important event for specification of the dorsal axis mesoderm during gastrulation. Recombination experiments showed that dorsal mesoderm-inducing activity was localized definitively in the endodermal epithelium (EE) of the lower marginal zone, with a dorso-ventral gradient; and the EE itself differentiated into endodermal tissues, mainly pharyngeal endoderm. Nevertheless, when dorsal EE alone was transplanted into the ventral region, a secondary axis with dorsal mesoderm was barely formed. However, when dorsal EE was transplanted with the bottle cells which by themselves were incapable of mesoderm induction, a second axis with well-developed dorsal mesoderm was observed. When the animal half with the lower marginal zone was rotated 180° and recombined with the vegetal half, most of the rotated embryos formed only one dorsal axis at the primary blastopore side. The present results suggest that there are at least two essential processes in dorsal axis formation: mesoderm induction of the upper marginal zone by endodermal epithelium of the lower marginal zone, and dorsalization of the upper dorsal marginal zone evoked during involution.
从蝾螈原肠胚形成初期分离出的上边缘区尚未确定会形成背轴中胚层，即脊索和肌肉。在本实验中，我们将指出背中胚层诱导活性在极早期原肠胚中的定位，以及原肠胚形成过程中背轴中胚层特化的重要事件是什么。重组实验表明，背中胚层诱导活性明确地定位于下边缘区的内胚层上皮（EE）中，呈背腹梯度分布；并且EE本身分化为内胚层组织，主要是咽内胚层。然而，当单独将背侧EE移植到腹侧区域时，几乎不会形成带有背中胚层的次生轴。但是，当将背侧EE与本身无中胚层诱导能力的瓶状细胞一起移植时，观察到带有发育良好的背中胚层的第二轴。当带有下边缘区的动物半球旋转180°并与植物半球重组时，大多数旋转后的胚胎仅在原肠胚孔侧形成一个背轴。目前的结果表明，背轴形成至少有两个基本过程：下边缘区内胚层上皮对上边缘区的中胚层诱导，以及内卷过程中诱发的上背边缘区的背化。
