Fig. 1.

Sperm morphology analyses for men with ARMC2 mutation. Normal morphology spermatozoa from a healthy man were revealed by light microscopy (A) and SEM (F). While in sperm from the man harboring homozygous ARMC2 mutation, multiple malformations can be observed, including short and irregular caliber (B, G), coiled (C, H), and absent (I) and bent (D) flagella. In addition, sperm with normal length can also be found in the ARMC2-deficient patient’s sperm (E). Under TEM, the cross-sections of the sperm from normal control show a typical “9 + 2” structure of microtubules and the regularly arranged outer dense fibrous sheath (J). Most of the sperm from the man with ARMC2 mutations show a severe disorder in the arrangement of the flagellar ultrastructure, especially the loss of the central pair of microtubules (K), and few are normal (L)