embryo sac

This term is a specialized botanical expression used primarily in plant biology and genetics. It describes the female gametophyte in angiosperms, serving as the site where the egg cell is housed and where double fertilization occurs. Because it is a technical term, it is almost exclusively found in academic textbooks, research papers, and scientific discussions regarding plant reproduction.

In a biological context, the embryo sac is distinct from the ovule; the sac is the cellular structure contained within the ovule. It is typically used in singular form when discussing the general mechanism of fertilization, but can be pluralized when referring to multiple structures across different ovules or species.