In Part I of this episode, which deals with human birth, we start with the Big Bang and follow a troop of sperm as they make their way to the ovum.

One lucky sperm has made it into the egg – now the chromosomes from the sperm and the egg can start to link up.

Cell division is now in full swing, and inside the embryo, the organs are being formed! All the cells now have to reach the places where they are needed.

The formation of the embryo is in full swing, and the cells are working diligently to create all of the different body parts!

More building blocks are needed to form the growing embryo — and the chromosome department is hard at work!

The last segment of this video focuses on gestation: Over the course of nine months, a single, fertilized egg becomes a baby!