Following compatible pollination, the pollen grain germinates on the stigma to produce a pollen tube through one of the germ pores. The contents of the pollen grain (2-mole nuclei) move into the pollen tube. Pollen tube grows through the tissues of the stigma and reaches the ovary.
After reaching the ovary, pollen tube enters the ovule through the micropyle and then enters the embryo sac by passing into one of the synergids through the filiform apparatus. It leads to the degeneration of that synergid.
The pollen tube breaks to release its contents (2 male nuclei). Out of the two male gametes one fuses with egg and the other fuses with central cell and fertilize.

The component cells of the egg-apparatus in an embryo sac include two synergids, one egg cell and the filiform apparatus.