Pollen grain is the mother cell of male gametophyte. Development of male gametophyte begins inside the microsporangium. The microspore nucleus divide myopically to -form a smaller generative cell and a much larger, vegetative cell (tube cell). The generative cells produces two male gametes. Whereas the vegetative cell form pollen tube after pollination. Pollen grain .contains two cell i.e., Tube cell and generative cell at the time of pollination.