Cai L, Hayes N L, Nowakowski R S
Department of Neuroscience and Cell Biology, Rutgers University and University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.
J Neurosci. 1997 Mar 15;17(6):2079-87. doi: 10.1523/JNEUROSCI.17-06-02079.1997.
We have measured the amount of variation in the length of the cell cycle for cells in the pseudostratified ventricular epithelium (PVE) of the developing cortex of mice on embryonic day 14. Our measurements were made in three cortical regions (i.e., the neocortex, archicortex, and periarchicortex) using three different methods: the cumulative labeling method (CLM), the percent labeled mitoses (PLM) method, and a comparison of the time needed for the PLM to ascend from 0 to 100% with the time needed for the PLM to descend from 100 to 0%. These 3 different techniques provide different perspectives on the cytokinetic parameters. Theoretically, CLM gives an estimate for a maximum value of the total length of the cell cycle (TC), whereas PLM gives an estimate of a minimum value of TC. The difference between these two estimates indicates that the range for TC is +/-1% of the mean TC for periarchicortex, +/-7% for neocortex, and +/-8% for archicortex. This was confirmed by a lengthening of the PLM descent time in comparison with its ascent time. The sharpness of the transitions and the flatness of the plateau of the PLM curves indicate that 99% of the proliferating cells are within this narrow estimated range for TC; hence, only approximately 1% deviate outside of a relatively restricted range from the average TC of the population. In the context of the possible existence within the cortical PVE of two populations with markedly dissimilar cell cycle kinetics from the mean, one such population must comprise approximately 99% of the total population, and the other, if it exists, is only approximately 1% of the total. This seems to be true for all three cortical regions. The narrow range of TC indicates a homogeneity in the cell cycle length for proliferating cells in three different cortical regions, despite the fact that progenitor cells of different lineages may be present. It further predicts the existence of almost synchronous interkinetic nuclear movements of the proliferating cells in the ventricular zone during early development of the cerebral cortex.
我们测量了胚胎第14天小鼠发育中皮层假复层心室上皮（PVE）细胞的细胞周期长度变化量。我们在三个皮质区域（即新皮质、古皮质和围古皮质）使用三种不同方法进行测量：累积标记法（CLM）、标记有丝分裂百分比（PLM）法，以及比较PLM从0上升到100%所需时间与从100下降到0%所需时间。这三种不同技术提供了关于细胞动力学参数的不同视角。理论上，CLM给出细胞周期总长度（TC）最大值的估计值，而PLM给出TC最小值的估计值。这两个估计值之间的差异表明，围古皮质TC范围为平均TC的±1%，新皮质为±7%，古皮质为±8%。与上升时间相比，PLM下降时间的延长证实了这一点。PLM曲线的转变锐度和平原平整度表明，99%的增殖细胞处于TC的这个狭窄估计范围内；因此，只有约1%的细胞偏离群体平均TC的相对受限范围。在皮质PVE中可能存在与平均值明显不同的细胞周期动力学的两个群体的背景下，其中一个群体必须约占总人口的99%，另一个群体（如果存在）仅约占总人口的1%。所有三个皮质区域似乎都是如此。TC的狭窄范围表明三个不同皮质区域增殖细胞的细胞周期长度具有同质性，尽管可能存在不同谱系的祖细胞。它进一步预测在大脑皮层早期发育过程中，脑室区增殖细胞存在几乎同步的动核运动。
