This paper presents a method of overlapping/aggregating nuclei cells segmentation. This method is based on the watershed segmentation algorithm, but the specificity of this work is to introduce some prior information about the usual shape of normal/pathological nuclei cells. Such prior information will help to optimize the right set of markers, from which the flooding will be done. This approach has been implemented and tested, and the results evaluated by cell biology experts show the efficiency of the proposed approach.