Proportionally fewer cysts are found in division in the testes of mutant males compared to wild type. Chromosome behaviour is abnormal in both meiotic divisions.

Spermatid cysts contain less than 64 but always more than 32 nuclei, which vary in size. First meiotic spindles are mostly abnormal, and second meiotic spindles are never seen. Monastral, deformed, diastral and multipolar spindles are found within the same first meiotic cyst. Although second meiotic spindles are not visible, second meiotic chromosomal configurations are seen at a frequency approaching wild type. In anaphase I, mostly bivalents and not dyads are moving to the poles, but sometimes precocious centromere separation results in anaphase II configurations within anaphase I cells. Abnormal centriole behaviour is also seen. Two types of spermatid nuclei are seen. In the first type, 0-4 detached centrioles are found in the cytoplasm of early spermatids. The centriolar bodies plus the tails are held together, probably by nebenkern derivatives, close to but detached from the nuclear membrane. In the second type, one centriole of a pair is attached, the other, though in near vicinity, is detached. The sperm heads are deformed and are found spread along the length of the tail bundle, never attached to the basal body end of the tails.