Although nuclear channels (NC) have been described in a variety of cells, their function has not been fully investigated. This investigation used immunofluorescent techniques to examine the formation and function of NC in HeLa cells, a human cervical cancer cell line. NC are defined as invaginations of the nuclear envelope (NE) that traverse the nucleoplasm, thus forming a ring-like nucleus. The resulting tunnel is devoid of nucleic acid and may contain cytoplasmic elements. to date, all the reports of the presence of NC are from electron microscopic investigations, which clearly demonstrate the occurrence of NC in the presence of what appear to be interphase nuclei. This investigation was initiated because the NC that we observed in HeLa cells could be seen with fluorescent microscopy and only appeared during telophase and early interphase.

HeLa cells, obtained from American Type Culture Collection, were cultured on glass coverslips in minimum essential medium (MEM) containing 5% calf serum (CS) and a mixture of 5% CO2 in air at 37°C.