Microzonal projection and climbing fiber remodeling in single olivocerebellar axons of newborn rats at postnatal days 4–7
Microzonal projection and climbing fiber remodeling in single olivocerebellar axons of newborn rats at postnatal days 4–7
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DOI：
10.1002/cne.20531
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发表时间：
2005-06
影响因子：
2.5
通讯作者：
I. Sugihara
中科院分区：
文献类型：
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作者：
I. Sugihara
成年橄榄小脑轴突分叉成大约七个攀爬纤维，这些纤维支配排列在纵向微区中的单个浦肯野细胞。为了阐明这一预测的发育基础，在出生后 4-7 天的大鼠下橄榄注射生物素化葡聚糖胺，对单个橄榄小脑轴突进行标记。单个橄榄小脑轴突和攀爬纤维的单个末端轴的整个轨迹是从小脑和延髓的连续切片重建的。单轴突分支成攀爬纤维，终止于与成人微区相当的狭窄带状区域。这表明橄榄小脑微区是预先确定的。攀缘纤维末端乔木由松散的爬行型，经过中间过渡型，改造为密集的巢状型。每个橄榄小脑轴突在爬行阶段有大约 100 个新生攀爬纤维，而每个轴突在巢阶段有大约 10 个攀爬纤维和大约同样多的萎缩攀爬纤维。这种减少表明，过多的新生攀缘纤维随着剩余攀缘纤维的重塑而退化。萎缩的末端乔木和非攀缘纤维的细侧络被认为是退化攀缘纤维的中间形式。攀爬纤维的这种重塑和退化可能与攀爬纤维-浦肯野细胞突触的电生理退化有关。攀缘纤维的重塑最早发生在第 VIII 小叶（尾部）和 IXa-b，然后是在小叶 IXc 和 X。与其他区域相比，这些区域中更发达的颗粒层表明皮质环境触发了攀缘纤维重塑。 J.Comp。内罗尔。 487:93–106, 2005。© 2005 Wiley-Liss, Inc.
An adult olivocerebellar axon ramifies into about seven climbing fibers that innervate single Purkinje cells arranged in a longitudinal microzone. To clarify the developmental basis of this projection, individual olivocerebellar axons were labeled with biotinylated dextran amine injected into the inferior olive in rats at postnatal days 4–7. The entire trajectories of single olivocerebellar axons and single terminal arbors of climbing fibers were reconstructed from serial sections of the cerebellum and medulla. Single axons ramified into climbing fibers that terminated in a narrow band‐shaped area comparable to the adult microzone. This indicated that olivocerebellar microzones are predetermined. Terminal arbors of climbing fibers were remodeled from loose creeper type, through intermediate transitional type, into dense nest type. Each olivocerebellar axon had some 100 nascent climbing fibers in the creeper stage, whereas each axon had about 10 climbing fibers and about as many atrophic climbing fibers in the nest stage. This decrease indicated that overabundant nascent climbing fibers degenerate concomitantly with the remodeling of remaining climbing fibers. Atrophic terminal arbors and non‐climbing fiber thin collaterals were considered the intermediate forms of degenerating climbing fibers. This remodeling and degeneration of climbing fibers may be related to the electrophysiological regression of climbing fiber‐Purkinje cell synapses. The remodeling of climbing fibers occurred earliest in lobules VIII (caudal part) and IXa‐b, and then in lobules IXc and X. The more developed granular layer in these areas compared to other areas suggests that the cortical environment triggers climbing fiber remodeling. J. Comp. Neurol. 487:93–106, 2005. © 2005 Wiley‐Liss, Inc.