Waehlby Cell Clump Splitter performs object split and merge by shape on a labeling. This may greatly improve quality of a labeling, especially for cell segmentation.
If your Image contains a lot of holes, you may want to consider preprocessing the input with the "Fill Holes" node or other kinds of hole filling.
The method used was mainly inspired by a paper by C. Waehlby, "Combining intensity, edge and shape information for 2D and 3D segmentation of cell nuclei in tissue sections", and the method use by CellCognition (cellcognition.org).