Complex sentence: Generally speaking, the megaspore, or large spore, germinates into a female (egg-producing) gametophyte, which is fertilized by sperm produced by the male gametophyte developing from the microspore.
Split into simpler sentences: Generally speaking, the megaspore, or large spore, germinates into a female gametophyte, which produces egg cells. These are fertilized by sperm produced by the male gametophyte developing from the microspore.