How are the male gametophytes and the male gametes formed in angiosperms?

In the anthers of every stamen there are pollen sacs. Within the pollen sacs there are microspore mother cells, or microsporocytes. These cells undergo meiosis forming microspores. Every microspore by mitosis forms a pollen grain having one generative cell and one tube cell. The pollen grain is the male gametophyte.

When pollination occurs and the pollen grain makes contact with the stigma (the apex of the pistil) the tube cell elongates its cytoplasm form the pollen tube that grows towards the ovary. The generative cell separates forming two sperm nuclei (male gametes) that migrate by the pollen tube.