Q. How are the male gametes and the male gametophytes formed in angiosperms?
In the anthers of every stamen there are pollen sacs. Inside the pollen sacs there are microspore mother cells, or microsporocytes and these cells undergo meiosis forming microspores. Every microspore by mitosis forms a pollen grain containing one generative cell and one tube cell. The pollen grain is male gametophyte.
Once pollination occurs and the pollen grain makes contact with the stigma (the apex of the pistil) the tube cell elongates its cytoplasm forming the pollen tube that grows towards the ovary. The generative cell splits forming two sperm nuclei (male gametes) that migrate through the pollen tube.