Tucker A S, Slack J M
Department of Zoology, Oxford University, UK.
Curr Biol. 1995 Jul 1;5(7):807-13. doi: 10.1016/s0960-9822(95)00158-8.
Although as humans we lose our tails in the second month of embryonic development, a persistent tail is a prominent structural feature of most adult vertebrates. Indeed, the post-anal tail is part of the definition of a chordate. The internal organization of the developing tail--with neural tube, notochord and paired somites--is the same as that of the main body axis, so it can be expected that the mechanism of tail formation has a close relationship to that of the vertebrate body plan as a whole. Despite this, almost nothing is known about how tails arise.
We present evidence to show that the tail bud of Xenopus laevis arises as the result of interactions between distinct zones of tissue at the posterior of the embryo at the neurula stage. These tissue interactions were demonstrated by manipulations of exogastrulae, which normally form no tail, and by transplantation experiments performed on the neural plate of stage 13 neurulae, whereby embryos with supernumary tails were produced.
We propose a new model of tail bud determination, termed the NMC model, to explain the results we have obtained. In this model, the tail bud is initiated by an interaction between two territories in the neural plate and a posterior mesodermal territory.
尽管作为人类，我们在胚胎发育的第二个月就失去了尾巴，但大多数成年脊椎动物都有一个明显的结构特征——残留尾巴。事实上，肛门后尾是脊索动物定义的一部分。发育中尾巴的内部结构——包括神经管、脊索和成对的体节——与主体轴相同，因此可以预期尾巴形成的机制与整个脊椎动物身体结构的机制密切相关。尽管如此，关于尾巴是如何产生的，几乎一无所知。
我们提供证据表明，非洲爪蟾的尾芽是神经胚阶段胚胎后部不同组织区域之间相互作用的结果。通过对通常不长尾巴的外胚层进行操作，以及对13期神经胚的神经板进行移植实验（由此产生了多余尾巴的胚胎），证明了这些组织相互作用。
我们提出了一种新的尾芽确定模型，称为NMC模型，以解释我们获得的结果。在这个模型中，尾芽是由神经板中的两个区域与后部中胚层区域之间的相互作用启动的。
