90% of cysts in division in mutant testes are in the first division, with most of them arrested in early anaphase. Anaphase movements of the chromosomes is quite regular, resulting in 32 diploid spermatids with nuclei of normal size. Rarely, second division does occur, and in these cases many anaphase plates show random distribution of all chromosomes. First division spindles are abnormal in shape; the spindle apparatus is shorter than normal and heavily loaded with mitochondria. There is also some discontinuity between the main body of spindle fibres and the zone of astral rays. Tripolar spindles are only rarely seen, and the relation between nuclear axis and spindle poles is normal. Mitochondria are equally distributed between the two poles and all nebenkern derivatives of the diploid spermatids are exceptionally regular and of equal size. The aggregation stages up to the "onion stage" are indistinguishable from those occurring in normal haploid cells. Most centrioles are attached in early spermatids, with two centriolar bodies being seen in each nuclear envelope, although detached centriolar bodies are quite frequent. The centriolar bodies undergo the same morphological transformations as in normal males. 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.

male-sterile