What is meant by monosporic development of female gametophyte?

What is meant by monosporic development of female gametophyte?

When the female gametophyte (embryo sac) develops from a single megaspore, it is called monosporic development.

Usually, in most angiosperms, the megaspore mother cell divides by meiosis to form four haploid megaspores arranged in a linear fashion. The three haploid megaspores situated towards the micropyle degenerate, while one remains functional which develops into the female gametophyte.