This paper presents a simulation-based method for the animation of the development of cellular layers. The neighborhood relations between the cells are determined using a simulated developmental process, expressed by the formalism of map L-systems. The cell shapes result from mechanical cell interactions. Two types of forces are considered: the osmotic pressure and the tension of cell walls. The animation consists of periods of continuous growth separated by instantaneous cell divisions. The method is illustrated using the fern gametophyte Microsorium linguaeforme.