Miller R H, Liuzzi F J
J Neurocytol. 1986 Apr;15(2):187-96. doi: 10.1007/BF01611655.
The amphibian spinal cord is characterized by the presence of radially oriented astrocytic glial cells. These cells have their somata located in the grey matter of the spinal cord and radial processes that extend from the soma through the grey and white matters to the pial surface of the cord. Here we show that these radial glial cells are the predominant cell type labelled by horseradish peroxidase (HRP) when the marker is applied to the surface of the cord. The morphology of the HRP-labelled processes of an individual cell is different as they pass through the grey and white matter regions of the cord. By indirect immunofluorescence on frozen sections we show that the binding of an antibody raised against mammalian glial fibrillary acidic protein (GFAP) is preferentially localized in those areas of the glial process that traverse the white matter of the spinal cord. By transmission electron microscopy we confirm that there are no astrocyte cell bodies either at the pial surface or throughout the white matter region of the cord. These results demonstrate that all the astrocytes in the adult frog spinal cord can be selectively labelled through the application of HRP to the surface of the cord, and that the processes of these labelled cells display regional morphological and biochemical specializations depending on their location in the cord. We propose that these astrocytes may play an important role in setting up the grey-white matter arrangement of the amphibian spinal cord and that a single astrocyte of the frog spinal cord may combine the properties and functions of both grey and white matter mammalian astrocytes.
两栖动物的脊髓以存在呈放射状排列的星形胶质细胞为特征。这些细胞的胞体位于脊髓灰质中，其放射状突起从胞体延伸穿过灰质和白质，直至脊髓的软膜表面。在此我们表明，当将辣根过氧化物酶（HRP）应用于脊髓表面时，这些放射状胶质细胞是被该标记物标记的主要细胞类型。单个细胞的HRP标记突起在穿过脊髓的灰质和白质区域时，其形态有所不同。通过对冰冻切片进行间接免疫荧光检测，我们发现针对哺乳动物胶质纤维酸性蛋白（GFAP）产生的抗体的结合优先定位于胶质突起穿过脊髓白质的那些区域。通过透射电子显微镜我们证实，在软膜表面或脊髓的整个白质区域均不存在星形胶质细胞的胞体。这些结果表明，通过将HRP应用于脊髓表面，可以选择性地标记成年青蛙脊髓中的所有星形胶质细胞，并且这些被标记细胞的突起根据其在脊髓中的位置表现出区域形态和生化特化。我们提出，这些星形胶质细胞可能在建立两栖动物脊髓的灰质 - 白质排列中起重要作用，并且青蛙脊髓中的单个星形胶质细胞可能兼具哺乳动物灰质和白质星形胶质细胞的特性和功能。
