Alterations in the organisation of cytokeratin filaments in normal and malignant human colonic epithelial cells during mitosis.

An ultrastructural analysis of the organisation of 10 nm intermediate filaments during mitosis, in normal and malignant human colonic epithelial cells present in resected material, was carried out. Similar changes in the integrity of the 10 nm filaments were seen both in normal mitotic cells (which have a highly specialised filamentous network during interphase), and malignant cells (which show a disorganised network during interphase). The 10 nm filaments were seen to shorten and 'fray' in early mitosis. This was associated with the formation of spheroidal aggregates of thin filaments and small granules, both free in the cytoplasm and associated with surface desmosomes. At mid-mitosis cells were essentially devoid of obvious filamentous material, (including the spheroidal aggregates). The filaments reformed in daughter cells after cytokinesis was completed.