Fig 8. Transmission electron microscopy (TEM) analysis confirms outer dynein arm (ODA) defects in sperm flagella and respiratory cilia from dynein preassembly mutant individuals.

(A) Electron micrographs of healthy control sperm show a regular flagellar 9+2 axoneme with clearly visible ODAs (indicated by blue arrowheads). Cross sections of sperm flagella of PCD-affected individuals (data shown for OP-516, OP-1899 II1, OP-3141 and OP-3399) confirm the absence and thus the ODA defect identified by high-resolution IF microscopy. (B) Analogously, axonemes of respiratory cilia of healthy control individuals show clearly visible and regularly disposed ODAs (indicated by orange arrowheads), whereas those of affected individuals lack the ODA complexes at their outer microtubule doublets. DNAAF7-mutant individual OP-6 II5 also displays some ciliary cross sections with ODAs still attached to microtubule doublets. Scale bars represent 200 nm.