Growth occurs through a combination of cell division and cell expansion.
Differentiation produces specialized cells and the overall form of the organism is the result of morphogenesis , due to pattern formation. The fate of cells will be determined at different points during development of embryos of different species. In some species, determination occurs relatively early in cleavage, in other species it occurs later. Figure 15.2 illustrates how tissue from early frog embryos has not been determined. Once determination has occurred, the fate of a tissue and its cells are sealed.