How does nuclear transfer differ when scientists use embryonic cells instead of adult body cells?

In nuclear transfer, the primary difference between using embryonic cells and adult body cells lies in the state of the donor nucleus and the subsequent requirement for reprogramming.

• Embryonic Cells: These cells are typically undifferentiated or less differentiated, meaning they possess a higher degree of totipotency or pluripotency. Because they are closer to the embryonic state, they are more easily accepted by the host egg to guide development.12
• Adult Body Cells (Somatic Cells): These cells are fully differentiated, meaning they have specialized functions and have "turned off" many genes required for early development. When used in somatic cell nuclear transfer (SCNT), the host egg must perform the complex task of "reprogramming" the adult nucleus—essentially reversing its differentiation to restore its ability to direct the development of a new organism.314

Historically, scientists believed only totipotent cells could guide development. However, experiments demonstrated that egg cells possess the remarkable ability to reprogram differentiated adult nuclei, a discovery that paved the way for cloning mammals like Dolly the sheep.12