Morphology of spermatozoa from two patients with a mutation in the FSIP2 gene. All spermatozoa from patients FSIP2_{_3} and FSIP2_{_4} have shorter flagella than controls with no mutation in the fibrous sheath interacting protein 2 (FSIP2) gene. Additional features of spermatozoa from men with the multiple morphological abnormalities of the sperm flagella (MMAF) phenotype, such as thick and coiled flagella, are also observed. Scale bars 10 μm.