Luskin M B, Boone M S
Department of Anatomy and Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA.
Chem Senses. 1994 Dec;19(6):695-714. doi: 10.1093/chemse/19.6.695.
A spatially discrete region of the anterior part of the postnatal telencephalic subventricular zone, referred to as the SVZa generates vast numbers of lineally-related neurons destined for the olfactory bulb (Luskin, 1993). The cells originating in the SVZa migrate to the olfactory bulb along a highly restricted pathway which is in a direction orthogonal to the orientation of radial glial fibers. In this study we analysed the number, distribution, orientation and rate of migration of SVZa-derived cells as they approach the olfactory bulb. In order to track the SVZa-derived cells, a retroviral lineage tracer, encoding the reporter gene E. coli beta-galactosidase (lacZ) was injected precisely into the rat SVZa at postnatal day 1 (P1). The lacZ-positive cells were visualized 1, 2 and 3 days later by X-Gal histochemistry in cryostat sections. As the number of SVZa-derived cells in the pathway increased with survival time, their distribution changed systematically. The distribution pattern of lacZ-positive cells by 2 and 3 days postinjection suggested that some of the progeny of infected progenitor cells were undergoing neurogenesis as they proceeded to the olfactory bulb; a large percentage of the lacZ-positive cells were substantially displaced from the SVZa injection site. To investigate whether lacZ-positive cells migrate in a directed fashion, their orientation preference was scored. For the majority of lacZ-positive cells (> 94%), their leading process was directed toward the olfactory bulb, possibly reflecting a response to migratory cues present along the pathway. The estimated average rate of cell migration to the olfactory bulb was 23 mu m/h, which is approximately twice the speed of radially directed neuronal migration from the telencephalic ventricular zone to the cortical plate (O'Rourke et al., 1992). Collectively, these results suggest that SVZa-derived interneurons en route to the olfactory bulb may employ a novel mode of tangential migration.
出生后端脑脑室下区前部的一个空间离散区域，称为SVZa，产生大量与嗅球有线性关系的神经元（卢斯金，1993年）。起源于SVZa的细胞沿着一条高度受限的路径迁移到嗅球，该路径与放射状胶质纤维的方向正交。在本研究中，我们分析了SVZa来源的细胞在接近嗅球时的数量、分布、方向和迁移速率。为了追踪SVZa来源的细胞，在出生后第1天（P1）将编码报告基因大肠杆菌β-半乳糖苷酶（lacZ）的逆转录病毒谱系示踪剂精确注射到大鼠的SVZa中。1、2和3天后，通过低温恒温切片中的X-Gal组织化学观察lacZ阳性细胞。随着路径中SVZa来源细胞的数量随存活时间增加，它们的分布发生了系统性变化。注射后2天和3天lacZ阳性细胞的分布模式表明，一些受感染祖细胞的后代在前往嗅球的过程中正在进行神经发生；很大比例的lacZ阳性细胞从SVZa注射部位明显移位。为了研究lacZ阳性细胞是否以定向方式迁移，对它们的方向偏好进行了评分。对于大多数lacZ阳性细胞（>94%），它们的前端过程指向嗅球，这可能反映了对沿路径存在的迁移线索的反应。估计细胞向嗅球迁移的平均速率为23μm/h，这大约是从端脑室区向皮质板径向定向神经元迁移速度的两倍（奥罗克等人，1992年）。总的来说，这些结果表明，前往嗅球途中的SVZa来源的中间神经元可能采用一种新的切向迁移模式。
