Possible patterns of nuclear rotation in binucleate hepatocytes in vivo: static examination with fluorescence and electron microscopy.

To demonstrate nuclear rotation in the intact organism, we induced the formation in vivo of internuclear chromatin bridges in binucleate hepatocytes and examined their morphological arrangement in static conditions. Fixed isolated hepatocytes were observed by fluorescence microscopy and solid liver tissue by electron microscopy. The morphological patterns provided information about different modalities of nuclear rotation, related to equatorial (stationary nuclei), peripheral (nuclei rotating in opposite direction) or oblique (nuclei rotating in the same direction) dispositions of chromatin bridges. Moreover, data indicate that the entire nucleus can rotate. The independence of the bridge arrangements from the cell cycle phases (G1, S, G2) suggests that the nuclear rotation is probably not due to exchange of substances between the active chromatin and the cytoplasm.