Normally each cell has a nucleus. However, cells of Vaucheria, Botrydium, Sphaeroplea, Penicillium, Opalina, Osteoclasts and Paramecium are more numerous. Multinucleated plant cells are called sinocytes. Animal cells with multiple nuclei are called syncytium. Stem cells, stem cells and mammalian red blood cells (except camels) do not have a nucleus. Nucleus may occupy 10-15% of cell space. About 90% of sperm are nuclei.