通过电镜对拟南芥野生型及ｅｐｎ型突变体小孢子发生和发育进一步研究（此突变体的特征是花粉从游离核时期就具有多核、多沟并有分枝的花粉管），值得注意的是突变体在发育至四核花粉母细胞时期，在整个母细胞原生质膜外开始形成小孢子的外壁（与野生型晚期四分体内单倍体小孢子原生质体外形成的外壁相同），此外，在突变体小孢子发生的整个过程中也未见到正常四分体的出现。因此，设想具有两个营养核、两个生殖核的突变体的大花粉直接由非正常的四核花粉母细胞形成，突变体发生缺失的时期在前减数分裂期或减数分裂Ⅱ Further studies on the microsporogenesis and development of the Arabidopsis thaliana wild-type and epn-type mutants by electron microscopy (this mutant is characterized by pollen, multiply ditch and branched pollen tubes from the free nucleus) is notable Is a mutant in the development of tetrad nuclear pollen mother cell period, starting in the entire plasma membrane of the outer membrane of the outer wall of microspores (wild type late tetrad haploid microspore protoplasts formed in the same outer wall), in addition, in the The occurrence of normal microspores did not show normal tetrad throughout the whole process. Therefore, it is hypothesized that large pollen with two vegetative and two reproductive nuclear mutants is directly formed by abnormal tetraploid pollen mother cells, with the absence of the mutant occurring in the pre-meiosis or meiosis II