Spicule Formation by Isolated Micromeres of the Sea Urchin Embryo
Spicule Formation by Isolated Micromeres of the Sea Urchin Embryo
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海胆胚胎的分离微团形成针状体
DOI：
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发表时间：
1975
期刊：
影响因子：
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通讯作者：
K. Okazaki
中科院分区：
文献类型：
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作者：
K. Okazaki
从三种日本海胆（Hemicentrotus pulcherrimus、Pseudocentrotus depressus和Anthocidaris crassispina）中分离出16细胞期的小孢子，并在含有少量马血清的海水中培养。在所有使用的物种中，分离的微小孢子首先不均等地分裂，就像它们在体内一样。随后分裂的模式和数量也与体内相同，尽管它们不一定在所有情况下都是清楚的，因为在某些批次的胚胎中，相邻细胞的边界在每个静止阶段变得不可见。
卵裂后，通过当单个细胞的轮廓是模糊的阶段，分离的微粒的下降形成类似于囊胚中的初级间充质细胞群的细胞聚集体。在这种聚集体中，出现一个针状的原基，它要么像正常的原肠胚一样发育成三辐射状的针状体，要么发育成杆状体。三辐状骨针生长成三维骨架，不仅在其最终形状和大小（包括种特异性特征）方面，而且在其发育过程和晶体学性质方面，与正常的pluteus骨架非常相似。另一方面，杆状体会发展成一维或二维的骨架。这些骨骼可能对应于完整骨骼的一部分。
Micromeres are isolated at the 16-cell stage from three species of Japanese sea urchins, Hemicentrotus pulcherrimus, Pseudocentrotus depressus , and Anthocidaris crassispina , and are cultured in sea water containing a small amount of horse serum. In all species used, isolated micromeres first divide unequally as they do in vivo. The pattern and number of the subsequent cleavages are also the same as in vivo, although they are not necessarily clear in all cases, since the border of the adjacent cells become invisible at each resting stage in some batches of embryos.
After cleavage, passing through the stage when the contours of the individual cell are obscure, decendants of the isolated micromeres form cell aggregates similar to the group of primary mesenchyme cells in a blastula. Within such aggregates, a spicular rudiment appears which develops either into a triradiate spicule as in normal gastrulae or into a rod. The triradiate spicule grows into a three-dimensional skeleton which is very similar to the normal pluteus skeleton, not only in its final shape and size including species-specific characters but in its developmental course and crystallographic nature. The rod, on the other hand, develops into either a one-dimensional or two-dimensional skeleton. These skeletons probably correspond to a part of the complete skeleton.