Development of the pollen grains and the formation of the male gametes

1) Each anther comprises four microsporangia (pollen sacs)
2) Each microsporangium contain large number of diploid microsporocytes / microspore mother cells     (2n)
3) Each microsporocyte undergoes meiosis to form four haploid microspore cells (n).
4) Each microspore then undergoes mitosis, producing a haploid male gametophyte (immature pollen     grain) consisting only two cells tube cell and a generative cell.
5) Immature pollen grain then is transferred from anther to stigma and germinate.
6) The nucleus of generative cell will divide by mitosis to form two male gametes. Pollen grains now      become mature gametophyte.
7) Tube cell produces the pollen tube, which delivers male gamete to the egg.