Angiosperms

In angiosperms, the female gametophyte is called embryo sac. It is formed by three micropylar cells collectively known as egg apparatus (one middle cell called egg or oosphere and two nuclei are called synergids, cooperative cells or help cells), three chalazal cells called antipodals and large central cell which has 2 polar nuclei. It contain 8 nuclei but 7 cells - 3 micropylar, 3 chalazal and one central i.e., (3 + 2 + 3).