Hunt R K, Jacobson M
Proc Natl Acad Sci U S A. 1973 Feb;70(2):507-11. doi: 10.1073/pnas.70.2.507.
The central connections of retinal ganglion cells are retinotopically organized, producing a "map" of the retina on the surface of the optic tectum. Exactly how and when individual ganglion cells develop the position-dependent properties (termed locus specificities) subserving formation of the map is unknown, but the positional information that each ganglion cell will use in this process is specified in the early Xenopus embryo during a critical period at stages 28-32. We report two methods for isolating eye primordia from the axial cues of the animals during this critical period and for then allowing the eyes to form retinotectal connections in a carrier embryo. The results show that, as early as optic vesicle stages 22-23, the eyes already contain orthogonal reference axes, that positional information can be specified with respect to these axes in vitro, and that the specification process itself may only entail a transition from a reversible to an irreversible state.
视网膜神经节细胞的中枢连接按视网膜拓扑结构组织，在视顶盖表面形成视网膜的“图谱”。单个神经节细胞究竟如何以及何时发展出有助于图谱形成的位置依赖性特性（称为位点特异性）尚不清楚，但每个神经节细胞在这一过程中所使用的位置信息在非洲爪蟾胚胎发育早期的关键阶段（第28 - 32期）就已确定。我们报告了两种方法，可在这一关键时期将眼原基从动物的轴向线索中分离出来，然后让眼睛在载体胚胎中形成视网膜 - 顶盖连接。结果表明，早在视泡阶段22 - 23，眼睛就已经包含正交参考轴，位置信息可以在体外相对于这些轴进行确定，并且确定过程本身可能仅涉及从可逆状态到不可逆状态的转变。
