Nuclear ghosts: a nonmembranous structural component of mammalian cell nuclei.

Electron micrographs of positively stained preparations of nonmembranous ghosts prepared from HeLa cell nuclei have revealed the presence of an array consisting of rodlike and annular structures interconnected by strands sensitive to deoxyribonuclease. This array is believed to be responsible for the spherical shape of nuclei that are free of membrane. In addition, a configurational change in this array may be associated with the cyclic dissolution and reformation of the nuclear envelope that accompanies mitosis in mammalian cells.