Abstract: 34

RELATIONSHIP BETWEEN HYPO-OSMOTIC SWELLING TEST AND SPERM PENETRATION ASSAY IN THAWED RAM SPERMATOZOA.

J Garde^{1 *}, M Pérez-Guzmán² , A Gutiérrez³
Dpto. Ciencia y tec. Agroforestal, UCLM, Albacete, Spain ¹
CERSYRA, Ciudad Real, Spain ²
Dpto. Reproducción Animal, INIA, Madrid, Spain ³

In the evaluation of cryopreserved ram semen, a number of sperm characteristics are evaluated. However, no attention has been given to assessing the fertilizing potential of a sample. An in vitro laboratory test, called Sperm Penetration Assay (SPA), was developed to check the ability of human sperm to penetrate zona-free hamster ova. Different researchers have compared SPA test results with basic semen parameters and the hypo-osmotic swelling (HOS) test in human spermatozoa, but not in rams. Thus, the aim of the present study was to correlate the ability of thawed ram spermatozoa to swell in a hypo-osmotic solution with different sperm variables as well as with their ability to penetrate zona-free hamster ova. Straws were thawed at 60°C for 8 sec and divided into 4 aliquots. One of the aliquots was subjected to a standard semen analysis to determine individual motility (IM), and acrosomal integrity (AI). The proportion of thawed spermatozoa that showed swelling in the hypo-osmotic (100 mOsm/kg) solution was evaluated in the second aliquot. The third aliquot was used to determine IM after incubation at 39°C for 60 min (IM60). In the last one, the ability of the spermatozoa to penetrate (percentage of penetration = PP) oocytes was determined by incubating them with denuded hamster ova. A high correlation (r= 0.86) was observed between the PP in a semen sample and the % of spermatozoa that were capable of undergoing swelling from the same sample. A good correlation (r= 0.74) was also observed between the PP and the % of IM60. By contrast, the correlations between PP in samples and % of IM and % of AI in the same samples were 0.56 and 0.53, respectively. Therefore, the HOS test to evaluate the functional integrity of the membrane of thawed ram spermatozoa is closely correlated to the in vitro fertilizing ability of spermatozoa.

    This abstract is being presented on Sunday, August 1 at 8:00 AM to 10:15 AM at CUB 2nd Floor Ballroom.