● Each cell of the sporogenous tissue in a microsporangium acts as a potential pollen mother cell (PMC) or microspore mother cell.
● PMC undergoes meiotic divisions to form cluster of four cells called microspore tetrad.
● On maturity, the anther dehydrates and the microspores separate from each other to form pollen grains.
● The newly differentiated pollen grain has a central nucleus and dense cytoplasm.
● The protoplast mitotically divides into two unequal cells—bigger vegetative cell which is rich in food reserve and smaller spindle-shaped generative cell with dense cytoplasm and a nucleus. This is called 2-celled stage.
● In majority angiosperms, pollens are released in this 2-celled stage, whereas in other species, the generative cell divides into 2 male gametes and thus pollen is said to be in 3-celled stage.