lkb1³¹⁵/lkb1⁷ larvae show mitotic defects in the brain. The mutant spindles show an overall microtubule density that is substantially lower than wild type. In approximately 80% of mutant spindles, asters are absent or severely reduced (this is a higher frequency than the 49% of control brains that have absent or severely reduced asters). Most mutant prometaphase and metaphase figures show low densities of both kinetochore and interpolar microtubules. Ana-telophases have central spindles that are thinner than those in controls. Mutant brains show an increase in the relative frequency of metaphase figures with respect to wild type. The mutant brains contain approximately 20% polyploid cells. The frequency of symmetric telophases is higher in the mutant brains than in wild-type controls.