Shatz C J
J Neurosci. 1983 Mar;3(3):482-99. doi: 10.1523/JNEUROSCI.03-03-00482.1983.
The prenatal development of connections between the retina and the lateral geniculate nucleus (LGN) was studied by means of the anterograde axonal transport of 3H-amino acids or horseradish peroxidase injected intraocularly in fetal cats older than embryonic day 27 (E27) and in newborn cats. (Gestation is 65 days.) A retinothalamic pathway exists as early as E28, when label can be seen in both ipsilateral and contralateral optic tracts. Afferents from the contralateral eye are the first to invade the anlage of the LGN by E32 with those from the ipsilateral eye following about 3 days later. Initially, the pattern of labeling within the nucleus is uniform, suggesting that the two sets of afferents must share a good deal of territory at early ages. By E47, however, gaps appear in the labeling pattern contralaterally, indicating that afferents from the two eyes are beginning to segregate from each other. Segregation continues so that by E54 it is possible to identify unambiguously regions of the LGN destined to comprise ipsilateral and contralateral eye layers. By birth, afferent input appears adult-like in organization, with the two sets of afferents almost completely segregated from each other into their appropriate layers. Cellular lamination of the nucleus has just commenced, however, thereby lagging the onset of afferent segregation by about 2 weeks. Prenatal development could be followed much more easily in the horizontal than in the coronal plane of section due to the finding here that the LGN is displaced approximately 90 degrees in the horizontal plane between E40 and E60. Measurements of the area occupied by the ipsilateral and contralateral afferents within the LGN indicated that even prior to segregation, the two sets of afferents are not completely intermixed within the LGN. On the contrary, those from the contralateral eye retain almost exclusive control of some territory throughout development. This detail contrasts with development in primates, in which intermixing of afferents from the two eyes is thought to be complete early on (Rakic, P. (1976) Nature 261: 467-471). Nevertheless, in the cat, as in other mammals, development of the retinogeniculate pathway is broadly characterized by an initial period of overlap followed by a period of segregation that gives rise to the adult pattern of afferent input.
通过向胚胎第27天（E27）之后的胎猫及新生猫眼内注射³H - 氨基酸或辣根过氧化物酶，利用顺行轴突运输的方法，研究了视网膜与外侧膝状体核（LGN）之间连接的产前发育情况。（妊娠期为65天。）早在E28时就存在视网膜丘脑通路，此时在同侧和对侧视束中都能看到标记。到E32时，来自对侧眼的传入纤维首先侵入LGN原基，来自同侧眼的传入纤维大约在3天后跟进。最初，核内的标记模式是均匀的，这表明两组传入纤维在早期一定共享了大量区域。然而，到E47时，对侧的标记模式出现了间隙，这表明来自两眼的传入纤维开始相互分离。分离持续进行，因此到E54时，可以明确识别出LGN中注定要形成同侧和对侧眼层的区域。出生时，传入输入在组织上看起来像成年期，两组传入纤维几乎完全相互分离到各自合适的层中。然而，核的细胞分层刚刚开始，因此比传入分离的开始晚约2周。由于在此发现LGN在E40和E60之间在水平面内大约移位了90度，所以在水平切片平面上比在冠状切片平面上更容易追踪产前发育情况。对LGN内同侧和对侧传入纤维所占面积的测量表明，即使在分离之前，两组传入纤维在LGN内也没有完全混合。相反，来自对侧眼的传入纤维在整个发育过程中几乎一直对某些区域保持着几乎排他性的控制。这一细节与灵长类动物的发育形成对比，在灵长类动物中，来自两眼的传入纤维早期被认为是完全混合的（拉基奇，P.（1976年）《自然》261：467 - 471）。尽管如此，在猫中，与其他哺乳动物一样，视网膜膝状体通路的发育大致特征是初期重叠期，随后是分离期，从而形成成年期的传入输入模式。
