Voigt T
Robert Bosch Vision Research Center, Salk Institute for Biological Studies, San Diego, California 92138-92093.
J Comp Neurol. 1989 Nov 1;289(1):74-88. doi: 10.1002/cne.902890106.
Coronal sections of the cerebral wall from developing ferrets (newborn to adult) were double-stained with antibodies to vimentin and glial fibrillary acidic protein (GFAP). At birth, the dominant glial population was radial glia and these cells labeled only for vimentin. A small population of immature astrocytes in the cortical plate was double labeled for GFAP and vimentin. In successive days, the number of vimentin-positive radial glia gradually decreased and they disappeared entirely at about 21 days. During this same period, the double-stained astrocytes increased in number and were distributed throughout the cortical plate and intermediate zone. After 6 weeks of age the astrocytes were mostly confined to the developing white matter. Around this time they gradually lost their vimentin staining, and in the adult no vimentin-positive elements were seen except at the ependymal surface. In newborn ferrets single radial glial cells were also visualized by applying the carbocyanine dye DiI onto the pial surface of fixed brains. While most radial glia extended from the ventricular zone to the pial surface, a substantial fraction of them had lost their contact to the ventricular zone. Their somata were displaced into the subventricular zone and lower portion of the intermediate zone. The possibility that radial glia transform into astrocytes was directly tested by injecting fluorescent dyes under the pial surface of newborn ferrets at a time when virtually no GFAP-positive astrocytes are present. The tracer, which was taken up in the upper portion of the cortical plate, stained the radial glial cell somata in the ventricular zone in a similar way as the dye DiI did in the fixed brains. As the radial glial cells disappeared at successively longer survival times, the tracer was ultimately found within newly formed GFAP-positive astrocytes. These results provide strong support for the hypothesis that radial glia cells are the immature form of astrocytes (Choi and Lapham: Brain Res. 148:295-311, '78; Schmechel and Rakic: Anat. Embryol. (Berl.) 156:115-152, '79), and also show that, at least in the ferret cortex, the transformation is accompanied by a change in the expression of intermediate filament protein.
对发育中的雪貂（从新生到成年）大脑壁的冠状切片用波形蛋白和胶质纤维酸性蛋白（GFAP）抗体进行双重染色。出生时，主要的胶质细胞群体是放射状胶质细胞，这些细胞仅对波形蛋白呈阳性标记。皮质板中有一小部分未成熟星形胶质细胞对GFAP和波形蛋白呈双重阳性标记。在接下来的几天里，波形蛋白阳性的放射状胶质细胞数量逐渐减少，并在大约21天时完全消失。在同一时期，双重染色的星形胶质细胞数量增加，并分布在整个皮质板和中间带。6周龄后，星形胶质细胞大多局限于发育中的白质。大约在这个时候，它们逐渐失去波形蛋白染色，在成年雪貂中，除了室管膜表面外，没有观察到波形蛋白阳性成分。在新生雪貂中，通过将羰花青染料DiI应用于固定大脑的软脑膜表面，也可以观察到单个放射状胶质细胞。虽然大多数放射状胶质细胞从脑室区延伸到软脑膜表面，但其中相当一部分已经失去了与脑室区的联系。它们的胞体移位到室下区和中间带的下部。通过在几乎没有GFAP阳性星形胶质细胞的新生雪貂软脑膜表面注射荧光染料，直接测试了放射状胶质细胞转化为星形胶质细胞的可能性。示踪剂被皮质板上部吸收，以与固定大脑中DiI染料类似的方式对脑室区的放射状胶质细胞胞体进行染色。随着放射状胶质细胞在相继延长的存活时间内消失，示踪剂最终在新形成的GFAP阳性星形胶质细胞中被发现。这些结果为放射状胶质细胞是星形胶质细胞的未成熟形式这一假说提供了有力支持（Choi和Lapham：《脑研究》148:295 - 311，'78；Schmechel和Rakic：《解剖学与胚胎学（柏林）》156:115 - 152，'79），并且还表明，至少在雪貂皮质中，这种转化伴随着中间丝蛋白表达的变化。
