A zygote (from Greek ζυγωτός zygōtos “joined” or “yoked”, from ζυγοῦν zygoun “to join” or “to yoke”), is an eukaryotic cell formed by a fertilization event between two gametes.
The zygote’s genome is a combination of the DNA in each gamete, and contains all of the genetic information necessary to form a new individual. In multicellular organisms, the zygote is the earliest developmental stage. In single-celled organisms, the zygote can divide asexually by mitosis to produce identical offspring.
Oscar Hertwig and Richard Hertwig made some of the first discoveries on animal zygote formation.