Enzymic protein content decreases from the maximum at early phase of proembryo stage (20.83%) to the minimum at young embryo (4.9%).

酶蛋白的最大含量在原胚阶段初为20.83%，以后至幼胚阶段急剧减少到4.9%。

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During early proembryo stage, the dorsiventrality appears in the proper of the embryo. On the ventral side, the cells are small with dense cytoplasm and few vacuoles.

原胚初期胚体出现背腹极性，腹面的细胞小，细胞质稠密，液泡较少；

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