Cellular Stage to Fetus

The fertilization of an egg cell by sperm in the uterine tube promotes the development of sexual division and the completion of a cell containing chromosomes of both parents. Human prenatal development is initiated with the fertilization of an ovum (egg) from a female by a sperm cell from the male. The chromosomes within the nucleus of a zygote (fertilized egg) contain all the genetic information necessary for the development and differentiation of body structures....

Anatomy Explorer

Full Cellular Stage to Fetus Description

[Continued from above] . . .

For the first eight weeks of its life, the fertilized egg is called the embryo. The embryo develops from an egg fertilized by the sperm. It begins as one cell, which divides into two cells by the times it descends from the fallopian tube into the uterus. These cells divide further until they form two groups - one making up the wall lining of the embryo to become the placenta and the second becoming the embryo itself.