<P> Human embryogenesis is the process of cell division and cellular differentiation of the embryo that occurs during the early stages of development . In biological terms , human development entails growth from a one - celled zygote to an adult human being . Fertilisation occurs when the sperm cell successfully enters and fuses with an egg cell ( ovum ) . The genetic material of the sperm and egg then combine to form a single cell called a zygote and the germinal stage of prenatal development commences . Embryogenesis covers the first eight weeks of development ; at the beginning of the ninth week the embryo is termed a fetus . Human embryology is the study of this development during the first eight weeks after fertilisation . The normal period of gestation ( pregnancy ) is nine months or 38 weeks . </P>
<P> Human embryogenesis is the process of cell division and cellular differentiation of the embryo that occurs during the early stages of development . In biological terms , human development entails growth from a one - celled zygote to an adult human being . Fertilisation occurs when the sperm cell successfully enters and fuses with an egg cell ( ovum ) . The genetic material of the sperm and egg then combine to form a single cell called a zygote and the germinal stage of prenatal development commences . Embryogenesis covers the first eight weeks of development ; at the beginning of the ninth week the embryo is termed a fetus . Human embryology is the study of this development during the first eight weeks after fertilisation . The normal period of gestation ( pregnancy ) is nine months or 38 weeks . </P>
what is the first cell of a human called
what is the first cell of a human called
zygote
zygote