Spore

noun A similar one-celled body in seed-bearing plants; the macrospore or microspore. The macrospore of seed-bearing plants develops into a female gametophyte or megagametophyte , which is contained within the ovule and eventually produces the egg cells. (The megagametophyte is also called the embryo sac in angiosperms.) The microspore of seed-bearing plants develops into the male microgametophyte or pollen grain.