The chromosomes in Klp67A^EP3516/Df(3L)29A6 mutant primary spermatocytes are abnormally dynamic and undergo exaggerated periods of reorientation during prometaphase. Unlike in wild-type spermatocytes, the chromosomes of mutant spermatocytes form poorly defined metaphase plates, which tend to be staggered with the chromosomes only loosely aligned. Additionally, the mutant chromosomes often do not find stable positions at the spindle equator and may exhibit one or more motions before anaphase onset. Prior to anaphase in the spermatocytes of Klp67A^EP3516/Df(3L)29A6 mutants, homologous chromosomes appear twisted relative to one another; this effect is not seen in wild type. During anaphase, chromosome movement does not occur in a continuous manner and poleward migration velocity is greatly attenuated compared to wild type. In some mutant cells dyads begin the migration poleward but then abruptly halt and remain stationary relative to the spindle pole, exhibiting no further poleward movement before decondensing. In a few cells it appears that disjoined dyads do not undergo any significant anaphase A movement. Nuclear reformation occurs at ectopic non-polar locations in 89% of Klp67A^EP3516/Df(3L)29A6 mutants.