Williams R W, Goldowitz D
Department of Anatomy and Neurobiology, University of Tennessee College of Medicine, Memphis 38163.
Proc Natl Acad Sci U S A. 1992 Feb 15;89(4):1184-8. doi: 10.1073/pnas.89.4.1184.
One of the most striking results of recent cell-lineage studies of vertebrate retina is the marked variability in the size and types of clones marked by retroviral transfection and dye injection of embryonic progenitor cells. Is this variability due to microenvironmental modulation of cell determination, to lineage restriction, or to experimental perturbation of the progenitor cells? We have taken advantage of species-specific DNA probes to mark groups of lineage-related cells in experimental mouse chimeras. This method of marking cells has two distinct advantages over previous methods: direct manipulation of progenitor cells is avoided, and clones are established at an earlier stage of retinal development. The most notable feature of retinal cohorts in chimeras is their structural uniformity--each is a solid radial array that contains the same ratio of major cell types as the retina itself. This is true even of the smallest monoclonal cohorts, which contain fewer than 200 cells. Our results provides compelling empirical support for the hypothesis that the murine retina is made up of hundreds of relatively homogeneous radial units, each derived from single retinal precursor cells. This finding is inconsistent with micro-environmental modulation of clone structure early in development. We raise the possibility that the heterogeneity among clones marked by dye injection and transfection is due to progressive lineage restriction or to experimental perturbation of the retinal progenitor cells.
脊椎动物视网膜近期细胞谱系研究最显著的结果之一，是通过逆转录病毒转染和对胚胎祖细胞进行染料注射所标记的克隆在大小和类型上存在显著差异。这种差异是由于细胞决定的微环境调节、谱系限制，还是祖细胞的实验性扰动所致？我们利用物种特异性DNA探针在实验性小鼠嵌合体中标记谱系相关细胞群。这种标记细胞的方法与以前的方法相比有两个明显的优点：避免了对祖细胞的直接操作，并且在视网膜发育的早期阶段就建立了克隆。嵌合体中视网膜群体最显著的特征是它们的结构一致性——每个群体都是一个坚实的放射状阵列，其主要细胞类型的比例与视网膜本身相同。即使是最小的单克隆群体也是如此，这些群体包含的细胞少于200个。我们的结果为小鼠视网膜由数百个相对同质的放射状单元组成这一假说提供了有力的实证支持，每个单元都源自单个视网膜前体细胞。这一发现与发育早期克隆结构的微环境调节不一致。我们提出一种可能性，即通过染料注射和转染所标记的克隆之间的异质性是由于渐进性的谱系限制或视网膜祖细胞的实验性扰动所致。
