A typical angiosperm embryo sac at maturity is:

The nucleus of the functional megaspore divides mitotically to form two nuclei which move to the opposite poles, forming the 2-nucleate embryo sac. Two more sequential mitotic nuclear divisions result in the formation of the 4-nucleate and later the 8-nucleate stages of the embryo sac.

There is a characteristic distribution of the cells within the embryo sac.

1. Three cells are grouped together at the micropylar end and constitute the egg apparatus. The egg apparatus, in turn, consists of two synergids and one egg cell.
2. Three cells are at the chalazal end and are called the antipodals.
3. The large central cell, as mentioned earlier, has two polar nuclei.

Thus, a typical angiosperm embryo sac, at maturity, though 8-nucleate is 7-celled.