The anterior-posterior axis is a central element of the body plan and, during amniote gastrulation, forms through several transient domains with specific morphogenetic activities. In the chick, experimentally proven activity of signalling molecules and transcription factors lead to the concept of a ‘global positioning system’ for initial axis formation whereas in the (mammotypical) rabbit embryo, a series of morphological or molecular domains are part of a putative ‘three-anchor-point model’. Because circular expression patterns of genes involved in axis formation exist in both amniote groups prior to, and during, gastrulation and may thus be suited to reconcile these models, the expression patterns of selected genes known in the chick, namely the ones coding for the transcription factors eomes and tbx6, the signalling molecule wnt3 and the wnt inhibitor pkdcc, were analysed in the rabbit embryonic disc using in situ hybridisation and placing emphasis on their germ layer location. Peripheral wnt3 and eomes expression in all layers is found initially to be complementary to central pkdcc expression in the hypoblast during early axis formation. Pkdcc then appears — together with a posterior-anterior gradient in wnt3 and eomes domains — in the epiblast posteriorly before the emerging primitive streak is marked by pkdcc and tbx6 at its anterior and posterior extremities, respectively. Conserved circular expression patterns deduced from some of this data may point to shared mechanisms in amniote axis formation while the reshaping of localised gene expression patterns is discussed as part of the ‘three-anchor-point model’ for establishing the mammalian body plan.

前后轴是身体平面的中心元素，在羊膜原肠胚形成过程中，通过几个具有特定形态发生活动的瞬时域形成。在小鸡中，经过实验证明的信号分子和转录因子的活性导致了用于初始轴形成的“全球定位系统”的概念，而在（乳房典型）兔子胚胎中，一系列形态或分子域是假定的“全球定位系统”的一部分。三锚点模型”。由于参与轴形成的基因的环状表达模式存在于原肠胚形成之前和期间的两个羊膜动物群中，因此可能适合协调这些模型，因此小鸡中已知的选定基因的表达模式，即编码转录的基因使用原位杂交在兔胚盘中分析因子 eomes 和 tbx6、信号分子 wnt3 和 Wnt 抑制剂 pkdcc，并重点关注它们的胚层位置。最初发现所有层中的外周wnt3和eomes表达与早期轴形成过程中下胚层中的中央pkdcc表达互补。然后， pkdcc与wnt3和eomes域中的后前梯度一起出现在后部的外胚层中，然后在其前肢和后肢分别用pkdcc和tbx6标记出现的原条。从这些数据中推导出来的保守圆形表达模式可能指向羊膜轴形成的共享机制，而局部基因表达模式的重塑则作为建立哺乳动物身体计划的“三锚点模型”的一部分进行讨论。