Inductive events in the patterning of the Xenopus laevis hatching and cement glands, two cell types which delimit head boundaries.
Inductive events in the patterning of the Xenopus laevis hatching and cement glands, two cell types which delimit head boundaries.
复制标题
非洲爪蟾孵化和水泥腺（界定头部边界的两种细胞类型）模式中的感应事件。
作者：
T. Drysdale;R. Elinson
在非洲爪蟾中，孵化腺和黏腺在头部的重要边界处形成。我们已经研究了这些腺体的诱导过程，以了解这种外胚层模式形成的基础。背中胚层和神经板可诱导外胚层形成孵化腺和黏腺。由于神经板足以诱导孵化腺和黏腺，并且在诱导时与假定的孵化腺和黏腺相邻，所以它是这些组织在体内诱导的最佳候选者。黏腺局限于头部前端，部分原因是前部而非后部神经板能够诱导它。孵化腺也局限于头部，但前部和后部神经板都可诱导它。因此，某种因素抑制了躯干部孵化腺的分化。移植的神经板片段在胚胎外胚层中诱导出孵化腺细胞，这表明诱导信号是平面性的。在原肠胚形成开始时用视黄酸或锂处理会导致头部结构缺失。在锂处理的胚胎中存在孵化腺，这表明这两种试剂具有不同的作用，并支持孵化腺和黏腺的诱导涉及不同途径的观点。
In Xenopus, the hatching and cement glands form at important boundaries in the head. We have examined induction of these glands in order to see the basis for this ectodermal patterning. Ectoderm can be induced to form hatching and cement glands by dorsal mesoderm and by the neural plate. Because the neural plate is sufficient to induce hatching and cement glands and lies adjacent to presumptive hatching and cement glands at the time of induction, it is the best candidate for the in vivo inducer of these tissues. The cement gland is restricted to the front of the head in part because the anterior but not posterior neural plate is capable of inducing it. The hatching gland is also restricted to the head, but can be induced by both anterior and posterior neural plates. Therefore, some factor suppresses hatching gland differentiation in the trunk. Transplanted neural plate pieces induced hatching gland cells in the ectoderm of embryos, suggesting that the inductive signal is planar. Treatment with retinoic acid or lithium at the start of gastrulation caused a loss of head structures. The presence of hatching gland in lithium-treated embryos suggests that these two agents have distinct effects and supports the idea that the induction of hatching and cement glands involves different pathways.