Luskin M B, McDermott K
Department of Anatomy and Cell Biology, Emory University School of Medicine, Atlanta, Georgia 30322.
Glia. 1994 Jul;11(3):211-26. doi: 10.1002/glia.440110302.
Although previous studies have revealed that the prenatal rat ventricular zone contains separate progenitor cells for neurons, astrocytes, and oligodendrocytes during the development of the cerebral cortex as early as the beginning of neurogenesis (Luskin et al., 1993; Grove et al., 1993), it is still unclear whether there are bipotential progenitor cells in the neonatal telencephalic subventricular zone which give rise to both astrocytes and oligodendrocytes during the peak of gliogenesis. To investigate this possibility, discrete groups of clonally related cells, generated by infecting progenitor cells of the neonatal subventricular zone with a retroviral lineage tracer, were analyzed ultrastructurally. An intracerebral injection of retrovirus encoding the reporter gene E. coli beta-galactosidase (lacZ) was made into the subventricular zone of newborn rats. Two weeks later their brains were perfused, sectioned, and histochemically reacted with X-Gal to identify at the light microscopic level clones of lacZ-positive cells. The sections were processed for electron microscopy to enable the identity of clonally related cells to be assessed at the ultrastructural level. All of the clones analyzed contained cells of the same phenotype and could be divided into four distinct types: immature cell clones situated in the subependymal zone surrounding the lateral ventricle, oligodendrocytes clones, and white or gray matter astrocyte clones. Not all of the cells in every clone displayed ultrastructural features of a mature cell. Rather, in some glial clones the lacZ-positive cells appeared to be at different stages of differentiation. However, we never encountered clones which contained both macroglial subtypes or clones containing neurons. Although the existence of bipotential progenitor cells cannot be completely dismissed, our results indicate the absence of progenitor cells in vivo in the neonatal subventricular zone which divide and generate astrocytes and oligodendrocytes.
尽管先前的研究表明，早在神经发生开始时，在大脑皮质发育过程中，产前大鼠脑室区就含有分别产生神经元、星形胶质细胞和少突胶质细胞的祖细胞（卢斯金等人，1993年；格罗夫等人，1993年），但目前仍不清楚在新生端脑的脑室下区是否存在双能祖细胞，这些祖细胞在胶质细胞生成高峰期产生星形胶质细胞和少突胶质细胞。为了研究这种可能性，我们对通过用逆转录病毒谱系示踪剂感染新生脑室下区的祖细胞而产生的离散的克隆相关细胞群进行了超微结构分析。将编码报告基因大肠杆菌β-半乳糖苷酶（lacZ）的逆转录病毒脑内注射到新生大鼠的脑室下区。两周后，对它们的大脑进行灌注、切片，并用X-Gal进行组织化学反应，以在光学显微镜水平上鉴定lacZ阳性细胞的克隆。对切片进行电子显微镜处理，以便在超微结构水平上评估克隆相关细胞的身份。所有分析的克隆都包含相同表型的细胞，并且可以分为四种不同类型：位于侧脑室周围室管膜下区的未成熟细胞克隆、少突胶质细胞克隆以及白质或灰质星形胶质细胞克隆。并非每个克隆中的所有细胞都显示出成熟细胞的超微结构特征。相反，在一些神经胶质克隆中，lacZ阳性细胞似乎处于不同的分化阶段。然而，我们从未遇到过同时包含两种大胶质细胞亚型的克隆或包含神经元的克隆。尽管不能完全排除双能祖细胞的存在，但我们的结果表明，新生脑室下区在体内不存在分裂并产生星形胶质细胞和少突胶质细胞的祖细胞。
