The two unequal-sized megaspores plus micropylar cell in the dyad formed a triad, in which callose disappeared in the chalazal end of the chalazal cell that developed into functional megaspore.

• 大多数情况下，珠孔端的二分体细胞在减数第二次分裂前或分裂的过程中退化，合点端的细胞分裂形成大小不等的两个细胞，形成三分体。