发布网友 发布时间:2023-11-21 13:51
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热心网友 时间:2024-07-26 19:29
that are roughly equivalent in size. In frogs, in which the egg has somewhat more yolk, cleavage proceedsmore rapidly in regions of the embryo having less yolk. In bird eggs the yolk is so massive thatcleavage divisions are restricted to a tiny area of cytoplasm.