ABSTRACT
As discussed in Chapter 1, the processes that control gene expression during cellular differentiation cannot be irreversible since it is possible for the DNA genome of a differentiated cell to give rise to an entire organism containing a wide variety of different cell types. This can occur for example, when differentiated plant cells are cultured under certain conditions or when the nucleus of differentiated animal cells is transplanted into an oocyte (see Chapter 1, Section 1.3).
