Cell nucleus
![HeLa cells stained for nuclear DNA with the Blue Hoechst dye. The central and rightmost cell are in interphase, thus their entire nuclei are labeled. On the left, a cell is going through mitosis and its DNA has condensed.](/Images/godic/202501/07/HeLa_cells_stained_with_Hoechst_332581625.jpg")
![](/Images/godic/202501/07/Animal_Cell.svg1625.png")
![Oldest known depiction of cells and their nuclei by Antonie van Leeuwenhoek, 1719](/Images/godic/202501/07/Leeuwenhoek1719RedBloodCells1625.jpg")
![Drawing of a Chironomus salivary gland cell published by Walther Flemming in 1882. The nucleus contains Polytene chromosomes.](/Images/godic/202501/07/Flemming1882Tafel1Fig141625.jpg")
In cell biology, the nucleus (pl. nuclei; from Latin nucleus or nuculeus, meaning kernel) is a membrane-enclosed organelle found in eukaryotic cells. Eukaryotes usually have a single nucleus, but a few cell types have no nuclei, and a few others have many.