Fig. 3. Transitory spindle poles during spindle formation in the incenp mutant. A time lapse sequence of spindle formation after nuclear envelope breakdown to metaphase I in wild type (A) and the incenp^QA26 mutant (B). Time zero indicated the first appearance of spindle microtubules (arrowheads) around the chromosomes. At 10:12 in the mutant, an ectopic pole (arrow) was formed around the spindle equatorial region and eventually merged with one of the poles. Scale bar: 10 µm.