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１９９６年以３０～３５年生白桦的雄性花序为材料，分期取样固定，利用ＯＬＹＭＰＵＳ显微镜进行观察。结果表明：６月底７月初出现小孢子母细胞，接着进入减数分裂过程。７月底８月初减数第一次分裂结束，随之减数第二次分裂开始，８月中旬分裂完毕，产生小孢子。从小孢子母细胞到产生小孢子历时约一个月左右。８月中旬之后便暂停发育，以单核小孢子越冬，次年４月末小孢子继续发育，经过一次或两次有丝分裂，于５月中旬形成成熟的雄配子体即花粉。白桦小孢子母细胞减数分裂过程中胞质分裂方式为同时型。四分体有三种存在形式。
In 1996, the male inflorescences of Betula platyphylla from 30 to 35 years old were taken as materials, and staged by sampling and observed by OLYMPUS microscope. The results showed that microspore mother cells appeared in late June and early July, and then entered the meiosis process. At the end of July and early August, the first division of the subtraction ends, followed by the second division of the lesser number. The division is completed in mid-August, resulting in microspores. From microspore mother cells to produce microspores about a month or so. After mid-August, the development was suspended and the mononuclear microspores overwintered. In the following year, the microspores continued to develop. After one or two mitoses, mature male gametophytes, pollen, formed in mid-May. The cytoplasmic cleavage patterns of microspore mother cells during meiosis were simultaneous. There are three forms of existence in the tetrad.