Fertilization occurs at the ampulla of the fallopian tube, and a zygote is formed by the fusion of an egg and a sperm. The first stage of prenatal development begins to start. This is the process of development of an embryo, and the process continues until birth. Also known as antenatal development, the very first stage in this phase is embryogenesis, in which the zygote is developed and it is a diploid cell now. It undergoes cellular divisions to form multicellular embryo.
