The two cells enclosed in a mature male gametophyte of an angiosperm are different . In anther of each stamen there are pollen sacs. Within the pollen sacs there are microscope mother cells or microsporocytes. Each microspore by mitosis forms a pollen grain containing one generative cell and one tube cell .
When pollination occurs and the pollen grain makes contact with the stigma , the tube cell elongates its cytoplasm forming the pollen tube that grows towards the ovary.
