Mori K, Ikeda J, Hayaishi O
Department of Neuroscience, Osaka Bioscience Institute, Japan.
Proc Natl Acad Sci U S A. 1990 Jul;87(14):5489-93. doi: 10.1073/pnas.87.14.5489.
Radial glial cells and their processes play critical roles in organizing the spatial arrangement of the nervous system in the embryonic brain. It has been thought that following completion of their roles in the embryo, most of the radial glial processes disappear before or shortly after birth. Here we use R2D5, a monoclonal antibody to a soluble cytosolic protein, to demonstrate that a specific system of midsagittal radial glial cells persists in postnatal and adult brain. In the brainstem of postnatally developing and adult rabbits and cats, the R2D5-positive processes of radial glial cells were observed to be arranged in a precisely parallel array at the midsagittal seam. These radial glial processes formed a continuous palisade separating the right and left brainstem. In early postnatal animals, R2D5-positive radial processes were found to reach the pial surface and to cover the entire midsagittal seam of the brainstem. These processes embraced dendrites and somata of neurons in almost all of the midsagittal nuclei, including the raphe nuclei, suggesting that the radial glial cells may interact with the midsagittal groups of neurons. In addition, the palisade of R2D5-positive radial processes formed loose openings for crossing axonal bundles at the midline decussations of fiber tracts. In more mature brains, somata of R2D5-positive radial glial cells that had migrated ventrally were observed within the palisades, and in adult cats, most of the R2D5-positive radial processes were found to have retracted from the ventral parts of the midsagittal seam. The spatial arrangement of R2D5-positive processes suggests that they may have persistent functional roles as an interface between ventricular humoral signals and midsagittal groups of neurons in the postnatally developing brainstem and in the adult brainstem. The structure of the midline glial system suggests also that it plays a role in organizing the spatial arrangement of decussating axons during development.
放射状胶质细胞及其突起在胚胎大脑中神经系统空间排列的组织过程中发挥着关键作用。人们一直认为，在胚胎期完成其作用后，大多数放射状胶质细胞的突起在出生前或出生后不久就会消失。在此，我们使用R2D5（一种针对可溶性胞质蛋白的单克隆抗体）来证明，中矢状放射状胶质细胞的特定系统在出生后及成年大脑中持续存在。在出生后发育的兔子和成年猫的脑干中，观察到放射状胶质细胞的R2D5阳性突起在中矢状缝处以精确平行的阵列排列。这些放射状胶质细胞突起形成了一个连续的栅栏，将左右脑干分隔开。在出生后早期的动物中，发现R2D5阳性放射状突起到达软膜表面并覆盖脑干的整个中矢状缝。这些突起包围了几乎所有中矢状核（包括中缝核）中的神经元树突和胞体，这表明放射状胶质细胞可能与中矢状神经元群相互作用。此外，R2D5阳性放射状突起的栅栏在纤维束的中线交叉处形成了松散的开口，用于轴突束的交叉。在更成熟的大脑中，在栅栏内观察到已向腹侧迁移的R2D5阳性放射状胶质细胞的胞体，并且在成年猫中，发现大多数R2D5阳性放射状突起已从中矢状缝的腹侧部分缩回。R2D5阳性突起的空间排列表明，它们可能作为出生后发育中的脑干和成年脑干中脑室体液信号与中矢状神经元群之间的界面，持续发挥功能作用。中线胶质系统的结构还表明，它在发育过程中对交叉轴突的空间排列起到组织作用。
