The embryologists found the realistic human organ models and animations of development necessary for their studies. The aim of this paper is to present a methodology producing a realistic animations of development. The convolution surface esgenerated by skeletons used for model representation are suitable for growth animation. The skeleton of a digestive system is a line skeleton with a tree structure. Therefore, its growth in length can be simulated by an algebraic L-system which controls the growth of skeleton segments. The global deformation of the skeleton due to the gravity and the lack of space in abdominal cavity are simulate d by a dynamics of skeleton segments. The known movements are implemented in our model by external forces applied on links controlling the organ movement in space. The entire system consists of two steps: First, the actual number of skeleton segments and the length of e ach skeleton segment is calculated from growth functions, second, the skeleton deformation in sp ace is updated based on dynamics.