The Cellular Potts Model (CPM) is a cellular automaton (CA) allowing to model the morphogenesis of living cells. It characterizes a cell by its volume, surface and type. The CPM has already been used to simulate several models of cell self-organization. However, the cell shape is under constraint i:e: it does not implies a unique shape. We propose a definition and an implementation of the cell shape in the CPM, that can target a unique shape. The results of our simulations show that this target shape can structure and maintain the cellular tissue since the beginning of its growth and during its life.