Burgess D R
Prog Clin Biol Res. 1977;17:569-79.
Ilyanassa eggs pinch off two polar bodies at the animal pole prior to the first cell division. During prophase and early metaphase the meiotic apparatus is separated from the cortex by a layer of lipid droplets and can be found in any orientation relative to the cell surface. As the astral microtubules grow, the meiotic apparatus appears to be pushed toward the animal cell surface by the expanding internal aster. By late metaphase and early anaphase the peripheral aster first flattens and then appears to be folded down around the spindle, as the peripheral half-spindle is extruded out of the egg. The internal aster and the spindle remain intact at telophase, while the peripheral aster disassembles. A cortical fine filamentous layer is present after early metaphase into which peripheral aster microtubules enmesh. Such an interaction may provide the means of attachment of the meiotic apparatus to the cell cortex. A band of microfilaments is organized around the neck of the forming polar body, and it is thought to act as a contractile ring. It is unlikely that the stimulus for meiotic cytokinesis is like that established for mitotic cytokinesis in eggs; i.e., the region of astral overlap during metaphase determines the site of the furrow, since during meiotic metaphase the region of astral overlap is in the cytoplasm well below the surface. The cleavage furrow does bisect the spindle.
在第一次细胞分裂之前，荔枝螺卵在动物极排出两个极体。在前期和早中期，减数分裂器被一层脂滴与皮质层隔开，并且相对于细胞表面可以呈任何方向。随着星体微管的生长，减数分裂器似乎被不断扩展的内部星体推向动物细胞表面。到晚中期和早后期，随着外周半纺锤体被挤出卵外，外周星体首先变平，然后似乎围绕纺锤体向下折叠。在末期，内部星体和纺锤体保持完整，而外周星体则解体。在早中期之后会出现一层皮质细丝层，外周星体微管会嵌入其中。这种相互作用可能提供了减数分裂器与细胞皮质附着的方式。在形成的极体颈部周围组织形成一条微丝带，人们认为它起到收缩环的作用。减数分裂胞质分裂的刺激因素不太可能与卵中有丝分裂胞质分裂所确定的刺激因素相同；也就是说，中期星体重叠区域决定了沟的位置，因为在减数分裂中期，星体重叠区域位于表面以下很深的细胞质中。分裂沟确实将纺锤体一分为二。
