玉米双受精过程的细胞学观察

1.玉米双受精属于有丝分裂前配子融合的类型。2.授粉后21至24小时,大部分雌、雄性核发生融合。雌、雄性核融合时,雄性核仁的出现存在两种情况,其一是精核染色质逐渐分散的同时出现雄性核仁,其二是精核染色质逐渐分散后,约经2至4小时才出现雄性核仁。3.合子内的雌、雄性核仁若发生融合,一般在合子分裂前进行。合子以一个大核仁的形式进入分裂期;雌、雄性核仁不融合的合子同样可以进入分裂期。授粉后30至33小时,合子进行第一次分裂。合子静止期大约为9小时左右。4.初生胚乳核内的雌、雄性核仁不发生融合。授粉后24至26小时,初生胚乳核进行第一次分裂。初生胚乳核的静止期为2—4小时。5.人工授粉条件下,玉米果穗受精过程的进行有一定的顺序;即自果穗上部逐渐向下部完成受精作用。

CYTOLOGIC OBSERVATIONS ON THE DOUBLE FERTILIZATION IN MAIZE

1.The double fertilization is the type of the premitotic syngamy.2.In 21 to 24 hours after pollination,most of the female nuclei fuse with the male nuclei.When the female nucleus fuses with the male nucleus,there are two situations in the appearance of the male nucleolus:one is that while the chromatin of the sperm nucleus relaxes gradually,a male nucleolus appears; the other is that after the chromatin of the sperm nucleus relaxes gradually,the male nucleus just appears in about 2 to 4 hours.3.Generally,the fusion of the female nucleolus with the male nucleolus takes place before the division of the nygote.The nygote enters the stage of division when it has a jarge nucieojus;the zygote,in which the female nucleolus does not fuse with the male nucleolus,also can enter the stage of division.In 30 to 33 hours after pollina- tion,the first division of the zygote occurs.The resting period of the zygote is about 9 hours. 4.In the primary endosperm nucleus,the female nucleolus does not fuse with the male nucle- olus.24 to 26 hours after pollination,the primary endosperm nucleus begins the first division. The resting period of the primary endosperm nucleus is 2 to 4 hours.5.Under the condition of artificial pollination,the fertilization of the fruit ears of maize proceeds sequencely,i.e.from the upper of the fruit ears to the lower the fertilization is fulfilled gradually.