Mitosis and cell death in the tail of the chick embryo
Mitosis and cell death in the tail of the chick embryo
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鸡胚胎尾部的有丝分裂和细胞死亡
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
R. Bellairs
中科院分区：
文献类型：
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作者：
C. L. Mills;R. Bellairs
虽然体节是从鸡胚尾部的中胚层开始发育的，但它们并没有形成到尾尖。先前的研究表明，这一终端中胚层具有许多特征的节板中胚层，从而产生体节的树干。因此，本研究旨在了解为什么终末中胚层不能形成体节。有丝分裂和固缩率已获得鸡胚尾区之间的阶段13和27。用秋水仙素处理胚，使有丝分裂阻滞在中期，并在连续切片上进行计数。总有丝分裂率在第15和18期之间最高。有丝分裂率高的区域，这是细胞同步性的指示，被发现在尾芽中胚层，虽然不是在一个一致的位置，只有很少的内尾节板的前端。然而，在躯干中（Stern和Bellairs 1984），通常在节段板的头端附近发现细胞同步性的单峰。它的结论是，尾巴中胚层的细胞是不同步的体节发生的准备比相应的中胚层细胞在躯干。进一步的结论是，尾芽本身不是一个高度增殖的区域，尽管有高有丝分裂率的补丁。整体固缩率在25阶段达到最大值;固缩峰最初与有丝分裂峰相对应，并与腹外胚层嵴和尾肠相关。然而，到第25阶段，高水平的细胞死亡主要限于尾尖。它的结论是，细胞死亡逐渐占主导地位的有丝分裂在该地区的前瞻性体节。此外，建议腹侧外胚层脊中的细胞可能发挥的作用，在模式形成类似的顶端外胚层脊在limb.Tail中胚层解剖胚胎在第13阶段（细胞死亡之前），和第16阶段（当补丁的细胞死亡已经建立），并在体外培养。在第13阶段的组织内发生的累积细胞死亡显著少于第16阶段。它的结论是，注定死亡的细胞可以至少部分地“获救”，如果在体外分离。
SummaryAlthough somites develop from the mesoderm in the tail of the chick embryo, they do not form to the tip of the tail. Previous work has shown that this terminal mesoderm possesses many of the characteristics of the segmental plate mesoderm which gives rise to the somites in the trunk. This investigation is aimed therefore at understanding why the terminal mesoderm fails to form somites.Mitotic and pyknotic rates have been obtained for the tail region of chick embryos between stages 13 and 27. Embryos were treated with colchicine, so that the mitoses were blocked in metaphase, and counts were made on serial sections. The overall mitotic rates were highest between stages 15 and 18. Regions of high mitotic rate, which are an indication of cell synchrony, were found in the tail bud mesoderm though not in a consistent location, and only infrequently ner the anterior end of the tail segmental plate. In the trunk however (Stern and Bellairs 1984) a single peak of cell synchrony was routinely found near the cranial end of the segmental plate. It is concluded that the cells of the tail mesoderm are less synchronised in preparation for somitogenesis than are the corresponding mesoderm cells in the trunk. A further conclusion is that the tail bud is not per se a region of high proliferation, though there are patches of high mitotic rate.The overall pyknotic rate reached a maximum at stage 25; peaks of pyknosis corresponded initially with the mitotic peaks and were associated with the ventral ectodermal ridge and the tail gut. By stage 25 however, the high levels of cell death were restricted mainly to the tip of the tail. It is concluded that cell death radually predominates over mitosis in the region of prospective somitogenesis. It is suggested moreover that the cells in the ventral ectodermal ridge may play a role in pattern formation similar to that of the apical ectodermal ridge in the limb.Tail mesoderm was dissected from embryos at stage 13 (prior to cell death), and stage 16 (when patches of cell death were already established), and explanted in vitro. The cumulative cell death which occurred within the tissue from stage 13 was significantly less that from stage 16. It is concluded that the cells destined for death may be at least partially “rescued” if isolated in vitro.