Quantitative and Qualitative Characteristics of Frozen-Thawed Bovine Spermatozoa Recovered Via a
Conventional and a Standardized Swim-Up Technique
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JUAN R. CORREA1,2, PANAYOTA N.
ZARMAKOUPIS-ZAVOS2,3 and
PANAYIOTIS M. ZAVOS1,2,3
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1Department of Animal Sciences, 2Andrology Institute of Lexington and
3Kentucky Center for Reproductive Medicine, Lexington, KY, USA
The objective of this study was to use the bovine as a model to evaluate the recovery of frozen-thawed
spermatozoa via a conventional and a standardized swim-up technique. Frozen-thawed semen specimens (3
bulls) were washed and reconstituted with 2.9% (w/v) sodium citrate extender contain-ing 20% (v/v) chicken
egg yolk (SC-EY). Reconstituted sperm specimens were used for selection via conventional swim-up and the
standardized ZSCTM method. The swim-up method consisted of ovarlayering the sperm
specimen with 0.7 to 1.0 ml of isolation media (Ham's F-10), followed by I hr of incubation. The
ZSCTM consisted of a conical cavity on the bottom of a glass column. The sperm specimen was
placed into the conical cavity until the surface of the specimen was at the same level as the upper boundaries of
the conical cavity. The surrounding periconical and epiconical areas were filled with 0.7 to 1.0 ml of isolation
media, followed by 1 hr of incubation. The isolation media was removed (harvesting) from swim-up (80%
volume) and ZSCTM specimens ( 100% volume) at the end of incubation. Recovered specimens
were assessed for volume (ml), sperm concentration ( x 106 spermatozoa/ml), the percentage and
grade of motility (0 to 4), the occurrence of osmotic shock and the percentage of spermatozoa reactive to the
hypoosmotic swelling (HOS) test. Swim-up and ZSCTM selected specimens were qualitatively
similar to each other. However, higher numbers of spermatozoa were recovered when sperm specimens were
processed via the ZSCTM method ( 1.6 fold increase) than with the conventional swim-up
technique. Because the ZSCTM method enabled the recovery of up to 100% of the overlayered
media, it also enabled the recovery of most of the spermatozoa that migrated from the sperm specimen into the
isolation media with no possibility of mixing the two, which was the case with the swim-up method, and which
could also contaminate the recovered specimen with dead and immotile spermatozoa. Thus, the
ZSCTM technique enabled the harvesting of the medium closest to the underlayered sperm
specimen, which contributed to maximize the number of sperm recovered. When all assessed parameters were
noted and all clinical improvements and efficiency of the method were compared to the swim-up technique, the
sperm manipulation procedure of choice was clearly the ZSCTM method.
Key words---
spermatozoa; swim-up techiques; sperm selection
Tohoku J. Exp. Med., 1997, 181, 267-274
Address for correspondence:
Professor, Panayiotis M. Zavos, Ed.S., Ph.D., 607 W.P. Garrigus Bldg., University of Kentucky, Lexington,
KY, 40546, USA.
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