According to Waddington, in his book The evolution of an evolutionist (1975), this term was borrowed by embryology from psychology. In developmental biology, it refers to the fact that cells not only increase in number during development, but also change in structure and function, and become different in their specializations from their earlier forms and from one another. During the 17th and 18th centuries, differentiation and growth constituted a battleground between the epigeneticists and the preformationists, with the former treating differentiation as the mechanism of development and the latter according growth the same status
See Cell theory, Dependent differentiation, Differentiation (embryology), Differentiation (specific), Epigenesis, Growth, Morphogenesis, Olfaction, Orthogenetic principle, Preformationism, Protein tyrosine kinase, Self-differentiation