Transient axonal branching in the developing corpus callosum.
Transient axonal branching in the developing corpus callosum.
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发育中的胼胝体中的瞬时轴突分支。
DOI：
10.1093/cercor/3.6.551
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Frost,DO
中科院分区：
文献类型：
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作者：
Kadhim,HJ;Bhide,PG;Frost,DO
在发育过程中，胼胝体中的轴突会出现短暂的过度生成；轴突的过度产生部分是由于通过胼胝体发送轴突的神经元短暂过量。然而，短暂的轴突分支也可能导致胼胝体轴突的发育过剩。为了研究这种可能性，我们用羰花青染料 1, 1'-双十八烷基-3,3,3',3'-四甲基吲哚碳花青高氯酸盐 (Dil) 填充叙利亚仓鼠中正在发育的胼胝体轴突。光学显微镜分析表明，事实上，仓鼠中胼胝体轴突分支的发育是短暂的：分支在出生后第 0 天 (P0) 和 P3（P0 = 出生后第一个 24 小时）非常强大，在 P6 和 P8 上不太明显，在 P11 时不存在。未成熟的胼胝轴突在穿过中线之前或之后以及胼胝体内的所有头尾部和内侧外侧水平分支。单个 100 μm 厚切片中包含的大多数胼胝体轴突侧枝相对较短（平均值 = 15.1 μm），但一些侧枝在离开观察到的切片之前从主轴突干延伸至~135 μm。几乎所有的侧支循环均源自轴突主干；高阶抵押品很少见。一些胼胝体轴突干有多个侧支。分支胼胝体轴突起源于多个皮质区域，包括区域 17。电子显微镜观察表明，根据光学显微镜标准指定为轴突侧支的过程将包含在发育中胼胝体轴突的电子显微镜计数中。一些胼胝体轴突干和分支具有超微结构特征，表明它们正在退化。在猫中，胼胝体轴突分支在胚胎第57天（E57；受孕后第一个24小时= E0）和P0发育。因此，未成熟的胼胝体轴突的短暂分支很可能是哺乳动物皮质发育的普遍特征，并且它有助于多个物种中胼胝体轴突的过度生产，尽管程度可能不同。
During development, there is a transient overproduction of axons in the corpus callosum; this overproduction of axons is due, in part, to a transient excess of neurons that send an axon through the corpus callosum. However, transient axonal branching could also contribute to the developmental overproduction of callosal axons. To investigate this possibility, we filled developing cal-losal axons in the Syrian hamster with the carbocyanine dye 1, 1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocy-anine perchlorate (Dil). Light microscopic analysis showed that, indeed, developing callosal axons branch transiently in the hamster: branching was robust on postnatal day 0 (P0) and P3 (P0 = the first 24 hr after birth), less prominent on P6 and P8, and absent by P11. Immature callosal axons branched before or after crossing the midline and at all rostral-caudal and medial-lateral levels within the corpus callosum. The majority of callosal axon collaterals that were contained within individual 100-μm-thick sections were relatively short (mean = 15.1 μm) but some collaterals extended up to ∼135 μm from the main axon trunk before passing out of the section in which they were observed. Nearly all of the collaterals emanated from the main axon trunk; higher-order collaterals were rare. Some callosal axon trunks had multiple collaterals. Branching callosal axons originated from multiple cortical areas, including area 17. Electron microscopic observations indicated that the processes designated as axon collaterals by light microscopic criteria would have been included in electron microscopic counts of developing callosal axons. Some callosal axon trunks and branches had ultrastructural features that suggested they were degenerating.In cats, developing callosal axons branch on embryonic day 57 (E57; the first 24 hr after conception = E0) and P0. Thus, it is likely that transient branching of immature callosal axons is a generalized feature of mammalian cortical development and that it contributes to the overproduction of callosal axons, albeit perhaps to varying degrees, in multiple species.