Pollen grains are structures in the seed plants (spermatophytes) which contain vegetative cells but also reproductive cells - microgametophytes. Microgametophytes produce 2 male gametes or sperm cells. Vegetative cells produce pollen tube which is involved in the transfer of sperm cells to the ovule (female structure that forms female gametes). Pollen grains are different in shape, size and color, but all of them are enveloped with hard coat that has protective role.
