Woodland H R, Jones E A
Department of Biological Sciences, University of Warwick, CV4 7AL, Coventry, Great Britain.
Rouxs Arch Dev Biol. 1988 Dec;197(7):441-446. doi: 10.1007/BF00398996.
We have used interspecific grafts between Xenopus borealis and Xenopus laevis to study the signalling system that produces tail mesoderm. Early gastrula ectoderm grafted into the posterior neural plate region of neurulae responds to a mesodermal inducing signal in this region and forms mainly tail somites; this signal persists until at least the early tail bud stage. Ventral ectoderm grafted into the posterior neural plate loses its competence to respond to this signal after stage 10 1/2. We have established the specification of anterior and posterior neural plate ectoderm. In ectodermal sandwiches or when grafted into unusual positions, anterior regions gave rise to mainly nervous system and posterior regions to large amounts of muscle, together with some nervous system. Thus it was impossible to assess the competence of posterior neural plate ectoderm to form further mesoderm and hence to establish if mesodermal induction continues during neurulation in unmanipulated embryos.
我们利用北方爪蟾和非洲爪蟾之间的种间移植来研究产生尾部中胚层的信号系统。早期原肠胚外胚层移植到神经胚的后神经板区域，会对该区域的中胚层诱导信号作出反应，并主要形成尾部体节；这种信号至少持续到早期尾芽阶段。移植到后神经板的腹侧外胚层在10.5期后失去了对该信号作出反应的能力。我们已经确定了前神经板外胚层和后神经板外胚层的特化。在外胚层三明治中或移植到异常位置时，前部区域主要产生神经系统，而后部区域则产生大量肌肉以及一些神经系统。因此，无法评估后神经板外胚层形成更多中胚层的能力，从而也无法确定在未受操作的胚胎中神经胚形成过程中中胚层诱导是否持续。
