The development of cytasters. During oogenesis (1 to 6), multiple accessory nuclei (purple) detach from the nuclear envelope (ne) and migrate towards the egg surface (2). The nuclear envelope breaks down ( dashed line, 3) and the centriolar precursor bodies (CPB, red points), which are placed in these membranous elements (3 and 4), develop into the centrioles (red circles) of the cytasters, which simultaneously nucleate microtubules of the asters ( green lines, 5). At the end of oogenesis (6), cytasters (green) have surrounded the egg cortex. Arabic numbers represent the sequence of events (not stages of meiosis). The polar body indicates the end of the first meiosis.