Effect of storage temperature on sperm cryopreservation.
OBJECTIVE
To evaluate the influence of cryopreservation temperature on human sperm motility and morphology.


METHODS
Controlled study, investigator was blinded to the type of cryopreservation.


METHODS
University-based andrology laboratory.


METHODS
Sixteen semen samples with normal motility and sperm count from men after a fertility work up.


METHODS
Semen aliquots were either stored in a mechanical freezer at -70 degrees C or in liquid nitrogen at -196 degrees C for 7 days or 3 months. Test yolk buffer was used as a cryoprotectant. With use of a programmable freezing unit, all samples were cooled at a controlled rate.


METHODS
Sperm motility and morphology.


RESULTS
After 7 days of cryopreservation, there was a greater decrease in sperm motility among specimens maintained at -70 degrees C than among those maintained at -196 degrees C (47% versus 39% decrease). The difference in sperm motility was even greater after 3 months of cryopreservation (72% versus 39% decrease). No difference in postthaw sperm morphology was detected among sperm preserved at -70 degrees C versus -196 degrees C.


CONCLUSIONS
Sperm cryopreservation at -196 degrees C is superior to cryopreservation at -70 degrees C. Sperm can be stored at -70 degrees C for a short period of time with a relatively modest loss of motility.
Trummer
H
H
Division of Urology, University of Colorado Health Science Center, Denver, USA. harald.trummer@kfunigraz.ac.at
Tucker
K
K
Young
C
C
Kaula
N
N
Meacham
R B
RB
D015925:Cryopreservation; D006801:Humans; D008297:Male; D013048:Specimen Handling / Q000379:methods*; D013081:Sperm Motility / Q000502:physiology*; D013696:Temperature