**4. Conclusion**

In this study, using the plant materials of several apomictic and obligately sexual varieties of bahia grass (*Paspalum notatum*) and the method of differential interference-contrast microscopy (DIC), we have clarified the mechanisms of aposporous embryo sac initial cell (AIC) appearance, the numbers of AICs increased as the ovary length grew before anthesis and AIC-derived apomictic embryo sac formation at anthesis, and after the anthesis, the process of polyembryonic seed formation by parthenogenesis. With the DIC technique giving the 3–D image recognition, AIC appearance, a different event from obligate sexual one, was firstly observed and recognized in *P. notatum*, so it could be expected as a related candidate with apomixis gene expression, as the *ASG-1*, an apomixis-specific gene-1 as reported in *P. maximum* based on the ovary length as an index to sample the AIC stage ovaries according to DIC observations [22, 24]. Therefore, the results of this study will be useful to provide the information on isolation of apomixis gene from apomictic varieties and the production of gene transgenic plants [17].
