Figure 6.

A working model of SEPT12 and α-/β-tubulins during spermiogenesis. (A) In the wild-type spermatozoa, SEPT12 forms the manchette structure of head, which is constituted with α-/β-tubulins. During sperm elongation, both SEPT12 and α-/β-tubulins are concentrated at the elongated midpiece to assure its structural integrity and facilitate tail formation. α-/β-tubulins are the major components of the axoneme of the mature sperm tail; (B) By reducing the SEPT12 level, the organization of α-/β-tubulins is disrupted. For spermatoza that are capable of completing tail elongation, they are presented with defective annulus with tail folded at 180 degrees (Upper panel). For spermatzoa with severe dysfunction of SEPT12 and α-/β-tubulins complex, disturbed structure of tail (middle) or round head with less tail. Red: α-/β-tubulins; green: SEPT12; Blue; nucleus.