SDF as determined by the SCD test. (a) Neat semen sample showing six sperm cells with fragmented DNA in the microscope field, as evidenced by the absence of a halo (red arrow), one sperm cell with degraded DNA, without a halo and weak or irregular staining (white arrow) and 11 sperm cells with intact DNA and a halo of dispersed DNA loops (green arrow). (b) SUP processed sample showing 20 sperm cells with intact DNA in the microscopic field, as evidenced by the presence of haloes. Scale bars=5 µm. SDF, sperm DNA fragmentation; SCD, sperm chromatin dispersion; SUP, swim-up.