In a fertilized ovule, n, 2n and 3n conditions occur respectively in

In a fertilized ovule, n, 2n and 3n conditions occur respectively in Egg, nucellus and endosperm.
In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the integument, forming its outer layer, the nucellus, and the female gametophyte in its center.
In flowering plants, one sperm nucleus fuses with the egg cell to produce a zygote, and the other fuses with the two polar nuclei of the central cell to give rise to the polyploid (typically triploid) endosperm. This double fertilization is unique to flowering plants, although in some other groups the second sperm cell does fuse with another cell in the megagametophyte to produce a second embryo.