Fig. 2. Organization of the meiosis II spindle. Projected series of optical sections of oocytes stained with anti-ß-tubulin antibody. (A) Late prophase: the peripheral MT network is dismantled, but small asters are still observed outside the spindle (arrows), the belt-shaped tubulin cluster is prominent and protruding at the spindle equator (large arrowhead); `minispindles' (small arrowheads) are focused at the outer poles. (B) Prometaphase: the interior MTs become focused on separate bundles of different size at the spindle equator (arrowheads), where short MTs spread out to form a loose cloud (arrow). (C) Late prometaphase: the interior MT bundles partially coalesce in three to four distinct bundles (arrowheads) that are focused at the spindle equator where MTs form an extensive astral array (arrow), the central aster. (D) Metaphase: the twin spindles have separated and the central aster (arrows) becomes clearly evident and enlarges during (E) anaphase and (F) telophase. Bar, 2 µm.