Intracellular position of G2/M-phase nuclei in neoplastic and non-neoplastic pseudostratified glands suggests the occurrence of interkinetic nuclear migration.

It has been established that nuclear pseudostratification of the neural epithelium in vertebral embryos is caused by interkinetic nuclear migration, a cell cycle-dependent regulation of nuclear movement, during which the G2/M-phase nuclei move apically before returning basally in the G1/S phase. Here we demonstrate the cell cycle-related nuclear location characteristic of interkinetic nuclear migration in human neoplastic and non-neoplastic pseudostratified glands. Immunohistochemical analysis with phosphohistone H3 (a G2/M-phase marker) and Ki67 was performed on fetal tissues, proliferative-phase endometrium (5 cases), and colonic adenomas (12 cases). In all cases, G2/M nuclei were significantly located apically, whereas Ki67-positive nuclei were widely distributed along the basal-apical axis. In the proliferating zone of the normal colon mucosa, elongated nuclei in the G2/M phase were occasionally found on the apical side of the cells. These results suggest that the interkinetic nuclear migration occurs in association with cell proliferation in both neoplastic and non-neoplastic glands.