Evaluation of the morphological and functional damage to human sperm subjected to freezing at -196°C and to refrigeration at -4°C

A study was carried out on five healthy, fertile donors to evaluate refrigeration at +4 C compared to cryopreservation at -196 degrees C. These donors had produced more than two pregnancies in different women with their cryopreserved semen in an AID program. The following parameters for evaluation and comparison were used: (i) the percentage of forward sperm motility, (ii) the percentage of swollen sperm after hypoosmotic stress (swelling test) and (iii) the sperm morphology observed both with a light microscope after staining and with an electron microscope. After 48 hours of refrigeration the result obtained were comparable with those observed after one week of cryopreservation. After 72 hours of refrigeration, a sharp and significant decrease of these values was noted. Our data underlined the fact that there is an individual variability in subject response to the method of preservation employed. Our findings show the possibility of using sperm refrigerated for up to 48 hours in AIH programs.