Embryonic sac

A megaspore mother cell, or megasporocyte, is a diploid cell in plants in which meiosis will occur, resulting in the production of four haploid megaspores. At least one of the spores develop into haploid female gametophytes (megagametophytes).^[1] The megaspore mother cell arises within the megasporangium tissue.

In flowering plants the megasporangium is also called the nucellus, and the female gametophyte is sometimes called the embryo sac or embryonic sac.