Harvesting Human ES Cells and Their Specialized Descendants       A Fertility Clinic Offer Its Help       A Global Struggle to Deal With Human ES Cells

Illustration: Rod Little

1. A human sperm fertilizes an egg.

2. The fertilized egg grows into a ball of 8 uniform cells.

3. The clump of cells develops into a blastocyst containing about 100 cells (the inner cell mass) surrounded by a transparent shell (the future placenta).

4. Cells taken from the inner cell mass are grown in a lab dish.

5. Result: a multipotent ES cell that can either renew itself or differentiate.

6. Differentiation into specialized cells.

Return to "Are Stem Cells the Answer?"

Return to "Are Stem Cells the Answer?"