FIGURE 1.

Sperm morphology analyses for men with CFAP251 variant. Normal morphology of spermatozoa from a healthy control male as revealed by light microscopy (A). The observed normal length of the sperm from a man harboring homozygous CFAP251 splicing variant (B). In addition, multiple malformations can be observed, including absent (C), short (D), coiled (E), bent (F) and irregular caliber flagella (G). Under TEM, the cross section of the normal sperm and very few sperm from men with CFAP251 variant show a typical “9+2” structure of microtubules and the regularly arranged outer dense fibrous sheath (H,I). Most of the sperm from the men with CFAP251 variant show a severe disorder in the arrangement of the flagellar ultrastructure (J). Central pair of microtubules (red arrows); peripheral microtubule doublet (yellow arrows).