细胞周期标记物在不同胚胎发育阶段小鼠脊髓内的分布模式

本研究用免疫组织化学方法观察了细胞周期全程标记物Ki-67和有丝分裂期标记物磷酸化的组蛋白H3(P-H3)在不同胚胎发育阶段小鼠脊髓的分布状况。结果显示:在胚胎第12d(E12)和E13,Ki-67标记细胞密集分布在脑室带(VZ)。E14以后,随着胎龄的增长,VZ内的Ki-67标记细胞逐渐减少,而套层内Ki-67阳性细胞的数量逐渐增多并于E17达到高峰。在此阶段,套层内Ki-67阳性细胞的数量占其阳性细胞总量的87.3%。在各胚胎阶段的脊髓内,VZ和套层内Ki-67阳性细胞的分布无背腹方向上的差异。P-H3标记细胞在胚胎发育阶段脊髓内分布的时空模式与Ki-67相似,其在套层内的分布同样于E17时达到高峰。另外,我们在E16之后的脊髓白质内还观察到了Ki-67和P-H3的标记细胞,以E18时数量最多。本研究结果提示,在胚胎发育晚期的脊髓套层内存在着具有增殖活性的神经祖细胞,它们可能是脊髓神经细胞产生的另外的来源。

THE DISTRIBUTION PATTERN OF CELL CYCLE MARKERS IN THE MOUSE SPINAL CORD DURING DIFFERENT EMBRYONIC STAGES

In the present study, immunohistochemical method was used to observe the distribution of cell cycle marker Ki-67 and mitotic phase marker phosphorylated histone H3 (P-H3) in the mouse spinal cord during embryonic development. The results showed that at embryonic day 12 (E12) and E13, Ki-67-labeled cells were densely distributed in the ventricular zone (VZ). After E14, the number of Ki-67-positive cells in the VZ decreased. In contrast, the number of Ki-67-positive cells in the mantle layer increased gradually and reached a peak at E17. At E17, Ki-67-positive cells in the mantle layer accounted for 87.3% of the total Ki-67-positive cells in the spinal cord. No difference in the distribution of Ki-67-positive cells in the ventral or dorsal parts of the VZ and the mantle layer was observed. The distribution of P-H3-labeled cells in the spinal cord showed a similar temporal and spatial pattern with that of Ki-67 and also reached a peak in number in the mantle layer at E17. We also observed Ki-67- and P-H3-positive cells in the white matter after E16 with the highest level at E18. The present results suggest the presence of proliferating cells in the spinal mantle layer at late embryonic stages. These neural progenitors might be another source of the spinal neuron production.