Comparison between glycerol and ethylene glycol for dog semen cryopreservation.
The aim of this study was to compare the effect of ethylene glycol versus glycerol for dog semen freezing, on post-thaw longevity, motility and motility parameters, and on plasma membrane functional integrity. Semen was diluted in two steps with an egg yolk TRIS extender containing a final concentration of either 5% glycerol or 5% ethylene glycol, and frozen in 0.5 ml straws, with 100 x 10(6) spermatozoa/ml, over nitrogen vapours. Semen motility was evaluated both under a light microscope and with a Computer Assisted Motility Analyser System, immediately after thawing and then hourly till 4h of incubation. Sperm membrane functional integrity was assessed with the hypoosmotic swelling test (60 mOsm fructose solution) applied at thawing and then hourly, for 4 h, on incubated samples. Motility (light microscope) and total and progressive motility (analyser) were significantly higher in ethylene glycol frozen samples at thawing (P < 0.01); from hour 1 onwards the effect of the cryoprotectant became not significant. Semen frozen with ethylene glycol showed higher path velocity and higher straight line velocity till 3 h after thawing; however, ethylene glycol semen samples also showed higher curvilinear velocity and higher lateral head displacement, which may indicate a capacitation-like condition affecting sperm membranes and possibly reducing post-thaw longevity. Functional integrity of plasma membrane was similar in glycerol and ethylene glycol samples till 3 h after thawing, then ethylene glycol samples showed a higher decline. The strong though short-lived positive effect of ethylene glycol is worth being evaluated further.
Rota
Ada
A
Department of Animal Pathology, Faculty of Veterinary Medicine, University of Turin, via Leonardo da Vinci 44, 10095 Grugliasco, TO, Italy. ada.rota@unito.it
Milani
Chiara
C
Cabianca
Giorgia
G
Martini
Marco
M
D000818:Animals; D002462:Cell Membrane / Q000502:physiology / Q000648:ultrastructure; D015925:Cryopreservation / Q000379:methods / Q000662:veterinary*; D003451:Cryoprotective Agents; D004285:Dogs; D019855:Ethylene Glycol; D005990:Glycerol; D006358:Hot Temperature; D008297:Male; D012662:Semen Preservation / Q000379:methods / Q000662:veterinary*; D013081:Sperm Motility; D013094:Spermatozoa / Q000502:physiology / Q000648:ultrastructure
D003451:Cryoprotective Agents; D019855:Ethylene Glycol; D005990:Glycerol