TOPOGRAPHICAL ORGANIZATION IN THE EARLY POSTNATAL CORTICOPONTINE PROJECTION - A CARBOCYANINE DYE AND 3-D COMPUTER RECONSTRUCTION STUDY IN THE RAT
TOPOGRAPHICAL ORGANIZATION IN THE EARLY POSTNATAL CORTICOPONTINE PROJECTION - A CARBOCYANINE DYE AND 3-D COMPUTER RECONSTRUCTION STUDY IN THE RAT
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DOI：
10.1002/cne.903610107
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发表时间：
1995-10-09
影响因子：
2.5
通讯作者：
BJAALIE, JG
中科院分区：
文献类型：
--
作者：
LEERGAARD, TB;LAKKE, EAJF;BJAALIE, JG
我们已经探索了基本规则指导早期发展的地形组织的投影，采用大鼠皮质桥脑投影作为模型系统。用1，1 ′，双十八烷基-3，3，3 ′，3 ′-四甲基吲哚羰花青高氯酸盐（DiI）顺行示踪法，研究了出生后第1周脑桥核内标记纤维与皮质起源部位的关系。假定的终末纤维通常占据片层状子空间。与皮质起源部位的变化相关，我们描述了脑桥核的内外侧、内外侧和尾侧分布梯度。起源于前外侧皮质的纤维占据了内部中央核心，而与前外侧皮质距离增加时，产生1）更多位于外部的椎板，以及2）纤维位置从尾侧向吻侧移位。先前的研究表明，脑桥小脑神经元以时间顺序迁移到腹侧围栏中（Altman和Layer [1987] J. Comp. Neurol. 257：529）。最早到达的神经元占据中央核心，较晚到达的神经元定居在更外部和嘴部定位的子空间。我们假设，最早到达的皮质桥脑纤维生长到当时唯一可用的区域的脑桥小脑神经元（中央核心），吸引了扩散性趋化性线索。后来到达的纤维生长成相应的更晚，更外部和嘴部位于脑桥小脑神经元的特遣队。因此，我们建议，在出生后早期的皮质脑桥投影的地形组织是由简单的时间和空间梯度源（大脑皮层）和目标区域（脑桥核）内的操作。(C)1995年Wiley-Liss，Inc.
We have explored basic rules guiding the early development of topographically organized projections, employing the rat corticopontine projection as a model system. Using anterograde in vivo tracing with 1,1', dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI), we studied the distribution of labelled fibers in the pontine nuclei in relation to cortical site of origin during the first postnatal week.Labelled corticopontine fibers enter the pontine nuclei in distinct, sharply defined zones. The putative terminal fibers typically occupy lamella-like subspaces. Related to changes in cortical site of origin, we describe mediolateral, internal to external, and caudorostral distribution gradients in the pontine nuclei. Fibers originating in the anterolateral cortex occupy an internal central core, while implantations at increasing distance from the anterolateral cortex produce 1) more externally located lamellae, and 2) a caudal to rostral shift in fiber location. Previous investigations have shown that pontocerebellar neurons migrate into the ventral pens in a temporal sequence (Altman and Layer [1987] J. Comp. Neurol. 257:529). The earliest arriving neurons occupy the central core and later arriving neurons settle in more externally and rostrally located subspaces. We hypothesize that the earliest arriving corticopontine fibers grow into the then only available zone of pontocerebellar neurons (central core), attracted by a diffusible chemotropic cue. Later arriving fibers grow into correspondingly later and more externally and rostrally located contingents of pontocerebellar neurons. Thus, we propose that the topographical organization in the early postnatal corticopontine projection is determined by simple temporal and spatial gradients operative within source (cerebral cortex) and target region (pontine nuclei). (C) 1995 Wiley-Liss, Inc.