INFO:

How does a single fertilized egg grow to become a fully formed human being? Many of the most critical stages happen in the first few days following conception. In this video segment from The Secret of Life, a fertilized egg cell progresses from its earliest stages through cell differentiation and ultimately the development of an embryo, with simple but identifiable body parts including a spinal cord, a heart, and eyes. This video is available in both English and Spanish audio, along with corresponding closed captions.