Fig 1. Study design for the selection of the motile sperm from the raw semen of lean, overweight, and obese men using the density gradient technique or the swim-up procedure.

Each semen sample was equally divided into two aliquots. Each aliquot was addressed to one of the motile sperm selection techniques. The concentration, motility, morphology, and nuclear composition (histone retention and DNA integrity) were assessed on the raw semen and on the selected motile spermatozoa (in the red circles). In addition, the detection of the reactive oxygen species (ROS) and the level of the DNA methylation/hydroxymethylation were performed on the motile sperm derived from the swim-up procedure from lean and obese men.