In this image we see the embryo 16-20 hours after fertilization, either conventional in vitro fertilization or ICSI. We appreciate the two polar bodies (PB) and the two pronuclei (PN): the maternal and the paternal. These last two will fuse to form the zygote, that is, an embryo of a single cell.
Embryo on day 1: zygote
Last Update: 06/20/2019