Fig. 2. The cytoplasmic spindle. (A-C) Phase-contrast images of living cells in prophase, revealing spindle-shaped cytoplasmic alignments outside the nucleus. (A) Bar, 10 µm. (B,C) Bar, 5 µm. (D) Labelling of a prophase cell with antibodies to tubulin reveals a spindle-shaped array of microtubules in the cytoplasm. The nucleus is at the bottom of the frame. Bar, 10 µm. (E) Prophase cell triple labelled to reveal acetylated tubulin (green), tyrosinated tubulin (red) and chromosomes (acridine orange labelling, which appears in the green channel). A spindle-shaped structure containing unacetylated microtubules is evident. The nucleus is at the bottom of the frame. Bar, 10 µm.