Fig. 1.

Ultrastructure of the axoneme. a Sperm axoneme of patient 1; b axoneme of nasal cilia cells of patient 1; c, d axonemes of nasal cilia cells of patient 2. Note absence of dynein arms (*) and nexin links (dotted line). 1 and 3, numbering of the peripheral duplets; A, microtubule A of a peripheral duplet; B, microtubule B of a peripheral duplet; dotted circle, central sheath; C1 and C2, central microtubule pair; black bar, radial spokes; FS, fibrous sheath. Scale bars, 25 nm