Zygote
Explanation - Zygote is the cell that undergo cleavage and divides to form embryo. Zygote is formed when ovum (female gamete) fuses with the sperm (male gamete). Therefore, zygote contain the genetic material of both male and female. Embryo then undergoes continual division to form morula.
Morula is a 16 celled stage. Morula then develops to form blastocyst which then gets implanted to the uterus for further development. The process of development takes 9 months in women and is called as gestation period.