Retinal ganglion beta cells project transiently to the superior colliculus during development.
Retinal ganglion beta cells project transiently to the superior colliculus during development.
复制标题
视网膜神经节β细胞在发育过程中短暂投射到上丘。
DOI：
10.1073/pnas.86.6.2061
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发表时间：
1989
影响因子：
11.1
通讯作者：
C. Shatz
中科院分区：
文献类型：
--
作者：
A. S. Ramoa;G. Campbell;C. Shatz
在成年猫中，β类视网膜神经节细胞几乎只投射到外侧膝状体核而不是上级丘（SC）。我们已经研究了这种靶特异性是否存在于早期发育过程中。为了鉴定在发育中向SC发送轴突的神经节细胞，将罗丹明标记的微球在胚胎第38天（E）、E43天或出生后第4天（P）沉积在SC中。然后在E56和P32之间取出视网膜，并在组织切片室中保持存活，以便用微球逆行标记的神经节细胞可以在细胞内注射荧光黄以揭示其形态学类别。在E38或E43时，许多β细胞可以被注射到SC中的微球逆行标记。他们是无法区分的β细胞投射到外侧膝状体核，并发现即使单次注射仅限于SC的尾侧部分。相反，β细胞不能逆行标记的微球注射到SC在P4。β细胞投射到SC的消失不能完全由细胞死亡解释，因为迟至P32，在神经节细胞死亡的主要时期之后，许多在E38用微球标记的β神经节细胞仍然存在。这些观察结果表明，许多β细胞最初将轴突侧支延伸到SC，随后在E43后一段时间丢失。因此，为了实现成人视觉系统中存在的显著特异性，β细胞必须从整个靶核中撤回轴突侧支。类似的侧支消除可能会引起其他感觉系统中传入连接的特异性。
In adult cats, retinal ganglion cells of the beta class project almost exclusively to the lateral geniculate nucleus rather than to the superior colliculus (SC). We have examined whether this target specificity is present during early development. To identify ganglion cells that send axons to the SC in development, rhodamine-labeled microspheres were deposited in the SC at embryonic day (E) 38, E43, or postnatal day (P) 4. Retinae were then removed between E56 and P32 and kept alive in a tissue-slice chamber so that ganglion cells that had been retrogradely labeled with microspheres could be injected intracellularly with Lucifer yellow to reveal their morphological class. Many beta cells could be retrogradely labeled by microspheres injected into the SC at E38 or E43. They were indistinguishable from beta cells projecting to the lateral geniculate nucleus and were found even when a single injection was restricted to the caudal portion of the SC. In contrast, beta cells could not be retrogradely labeled by microspheres injected into the SC at P4. The disappearance of a beta-cell projection to the SC cannot be explained entirely by cell death since as late as P32, well after the major period of ganglion cell death, many beta ganglion cells labeled with microspheres at E38 were still present. These observations suggest that many beta cells initially extend an axon collateral to the SC that is subsequently lost some time after E43. Thus, to achieve the remarkable specificity present in the adult visual system, beta cells must withdraw axon collaterals from an entire target nucleus. Similar collateral elimination may give rise to the specificity of afferent connections in other sensory systems.