Zygote - Embryogenesis
The fertilized egg or zygote is situated at the micropylar end/pole of the embryo sac, its basal (micropylar) end is attached to the embryo sac wall and apical (chalazal) part projects into the central cell. The zygote usually undergoes a period of rest during which it shrinks. This resting period of the zygote varies with different species and is to some extent dependent on environmental conditions e.g. in Theobroma cacao the zygote divides 14 to 15 days after fertilization, in Oryza saliva zygote divides about 6 hours after fertilization.
A complete cell wall is formed around the zygote. (You would dl that the egg has only plasmalemma and no wall at its apical part). A TEM picture shows that zygote cytoplasm show a more polarized appearance and that is the two poles appear different, micropylar part is vacuolate and chalazal part with a prominent nucleus.