The spermatids of a few cysts show coiling, but abnormalities are usually evident in elongating gametes in mutant males. Many spermatids have 2 or more axonemes associated with a single mitochondrial derivative. The mitochondrial derivatives form abnormal attachments to one or more membranes other than the normal axoneme attachment, and paracrystalline body formation appears to be initiated at all membrane attachements, including multiple sites within one derivative. Axoneme degeneration is seen in post-elongation gametes. Breaks in the axoneme are common. Coiling is not initiated in some cysts due to failure of the major mitochondrial derivative to elongate properly or because the paracrystalline body does not completely form. The spermatids do not completely individualise and subsequently degenerate. Spermatid head development proceeds normally to the elongation stage. Many cysts have fewer than 32 gametes per cyst, and some have more than 130.

Testes of mutant males contain no motile sperm.