Fig. 7. TEM analysis of microtubule organisation in apoptotic A431 cells. (A) Bundles of closely packed, intersecting microtubules (asterisks) seen in longitudinal section (LS) in the body of an apoptotic A431 cell. (B) Detail of an area of cytoplasm at the base of an apoptotic spike. A bundle of microtubules (arrowheads) can be seen in LS running into the spike. Intact mitochondria (Mch), chromatin (Ch), ribonucleoprotein granules (Rnp) and unidentified membrane-bound organelles are also apparent. (C) A microtubule (arrowheads) running parallel to the plasma membrane of an isolated cell fragment is shown in close-up in D. (E) Transverse section through an apoptotic spike. Microtubule profiles can be seen in the close-up of the boxed area (arrows in F). In each example, apoptosis was induced by UV irradiation.