What is Therapeutic Cloning and Why Do We Need It?

 These two diagrams illustrate therapeutic cloning, as described in the text below them.  Two of the arrows in the diagrams are misleading, however.  Note that the clonal embryo resulting from the first process is the source of the blastocyst used in the second process to culivate stem cells and then specialized cells for therapeutic use.

These diagrams illustrate only one aim of the research cloning of embryonic stem cells: the development of  cell-replacement therapies.  But research cloning may also make other valuable contributions  -- e.g., other kinds of cell-based treatments for diseases having a genetic component, safer testing of experimental medicines, and more ethnically diverse stem cell lines – that receive little media attention and are almost always overlooked by critics of therapeutic cloning. 

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