synergids and antipodal cells degenerate. One male gamete and the egg fuse to form the zygote (2N). The other male gamete fuses with the polar nuclei of the central cell to become the primary endosperm nucleus. This process of gametic fusion in angiosperms is called double fertilization. The primary endosperm nucleus divides repeatedly to produce the endosperm. Ploidy of the endosperm is dependent upon the number and ploidy of the nuclei that fuse in the central cell.