The 3-celled pollen grain of Angiosperm is considered to be mature male gametophyte where the terminal position has more of cytoplasm and tube-nucleus. The two male gametes remain in the back side of tube nucleus. Nearly 40% of Angiosperms release their pollen grain in 3-celled stage while rest of the 60% of angiosperm release pollen grain in 2-celled stage. The 2-celled stage is referred to as partially developed male gametophyte.