Practice question

Mammalian sperm flagellum core structure comprises microtubule-based axoneme anchored at basal body in neck region extending through midpiece and principal piece. Axoneme follows canonical 9+2 arrangement of nine doublet microtubules surrounding central pair, with outer dynein arms hydrolyzing ATP generating sliding between doublets converted to bending by radial spokes and nexin links. Accessory outer dense fibers and fibrous sheath provide elasticity. Microtubule dynamics drive progressive and hyperactivated motility; defects in axonemal components cause immotile cilia syndromes, primary ciliary dyskinesia, infertility due to impaired propulsion and flagellar function and reduced fertilization rates.