The dyad formed in Meiosis I was wrapped by thick callose.

• 粗/双线期，细胞的电子密度增加，细胞壁积累胼胝质，切断大孢子母细胞与珠心细胞之间的胞间连丝，核糖体的数量增多，线粒体与质体的形态变得不易区分，呈现脱分化状态。