Abstract: During the genesis of microspores and male gametes, the percentages of cells with an increas- ed and decreased chromosome number at metaphase Ⅱ, mitotic metaphase of microspores and generative cells approximated to the one at previous stage (metaphase Ⅰ, metaphase Il, and microspores) respectively, and the one at metaphase 1 again approximated to the percentages of chromatin intercellular migration of type 2.3→1 and 1→2.3 respectively, which had no significant diversity statistically. According to this fact, it was considered that the changes of chromosome numbers were related to the chromatin intercellular migration at synizesis stage and that pollen mother cells with an abnormal chromosome number at metaphase Ⅰ basically were able to continue developing untill the formation of male gametes.

Key words: Allium cepa, Microspore, Male gamete, Intercellular migration of chromaotin, Change of chromosome number