两栖类早期发育中一内胚层形成和神经板发育之垂直的和平面的诱导作用

中-内胚层诱导和神经诱导都需要平面的和垂直的诱导相互作用;中胚层诱导开初是一个平面诱导过程,继之以一个垂直诱导,以实现最终的区域分化,而神经诱导则必须有最初的垂直相互作用,以实现激发和转化过程。这些垂直的诱导作用,继之以在外胚层内传播的同源诱导作用,决定神经板的形状和大小,以及其区域分化。对于神经板的背面集中和伸长,激发作用和后来的转化作用似乎都是必需的。

VERTICAL AND PLANAR INDUCTION IN EARLY AMPHIBIAN DEVELOPMENT DURING MESO-ENDODERM FORMATION AND NEURAL PLATE DEVELOPMENT

Both meso-endoderm and neural induc-tion require planar as well as vertical in-ductive interactions;mesoderm inductionbeing initially a planar induction processfollowed by a vertical induction for itsultimate regional differentiation,whereasan initial vertical interaction is indispen-sable for neural induction both for theactivation and the transformation processes.These vertical inductions are then followedby planar,homoiogenetic spreading inside the ectodermal layer,determining the ul-timate form and size of the neural plateas well as its regional differentiation.Fordorsal convergence and stretching of theneural plate,both activation and subse-quent transformation seem to be required.