Fig. 1.

Multiple mechanisms lead to the same ploidy and nuclear number outcomes. Cycles with absent or incomplete karyokinesis can both yield increased nuclear size and ploidy. Cycles with full nuclear division but incomplete cytokinesis, as well as cell–cell fusion, increase the number of nuclei. Each blue arrow represents a doubling in genome content. Each black arrow represents an incomplete cytokinesis. Each red arrow represents the addition of the number of single nuclei adjacent to the arrow. This illustration does not depict reductive division, which can reverse increased cellular ploidy