The ultrastructure of spontaneous radial segmentation of the nuclei in bone marrow cells from 3 patients with acute myeloid leukaemia.

Bone marrow cells with spontaneous radial segmentation of the nuclei from three patients with acute myeloid leukaemia were analysed by means of electron microscopy. The centriole was found in the centre of the cluster of nuclear segments. Cytoplasmic microtubules were found in the intersegmental clefts and in the pericentriolar area. The present observations support the hypothesis that spontaneous radial segmentation of the nuclei in tumour cells is due to a microtubule-associated contractile process, by which the nucleus is folded into segments.