Chapter 30 Class Notes – Plant Diversity II: The Evolution of Seed Plants – Page 2The micropyle, the only opening through the integument, allows entry of a pollen grain, containing a male gametophyte, which develops a pollen tube that discharges sperm, thereby fertilizing the egg.Fertilization initiates the transformation of the ovule into a seed, which consists of a sporophyte embryo, a food supply, and a protective seed coat derived from the integument.Pollen and Production of Sperm:Microspores develop into pollen grains, which contain the male gametophytes.Pollination is the transfer of pollen to the part of a seed plant containing the ovule.Pollen can be dispersed by air or animals, eliminating the water requirement for fertilization.