When I was first approached to edit the present volume, I was somewhat reluc tant to undertake this humbling task because most of my own scientific expertise is derived fi'om studies of mammalian fertilization rather than somatic cell nuclear transfer (SCNT). However, in the last ten years, I was very fortunate to train, col laborate, and communicate with a number of distinguished "doners," many of whom kindly agreed to contribute to the present volume. This experience made me appre ciate that the understanding of cellular and molecular events during and after SCNT is deeply rooted in our...