Working model of SEPT-related complex during mammalian spermatogenesis. (A) We reason that SEPT12-related complex consists of SEPT12, SEPT1, 4, 6 and 7. In the wild-type spermatozoa, SEPT12 coils around the arcosome and is concentrated at the neck of sperm. With the formation of mitochondria, SEPT12 starts to express at the neck and annulus. The SEPT 12 filaments also cover the mitochondrial area. (B) Decreased expression of SEPT12, results in maturation arrest at the spermatid stage, broken acrosome, bent tails, disorganized mitochondria and nuclear DNA damage.