To solve the logistical problems of the sperm penetration assay (SPA) to provide just a sufficient number of hamster ova exactly when they are needed, a new method to cryopreserve the ova has been devised (1-step dehydration and 2-step thawing).
After
freezing & thawing of zona-intact (ZI) and zona-free (ZF) hamster ova according to this new method, the frozen-thawed ova were compared with fresh, control ova (FO) in terms of the degree of sperm penetration in SPA using semen samples from
fertile
donors, subfertile, and infertile male. Each sperm sample was capacitated for 42 hours in TEST-Yolk Buffer before insemination in SPA.
In fertile doner, both the penetration rate and penetration index were lower in SPA using frozen ova (ZI; 92.4%, 6.2, ZF; 63.7%, 3.9) than those of SPA using fresh ova (99.3%, 8.4). There was a significant correlation between the penetration
index
of
SPA using FO and ZI (p<0.001), and between those of SPA using FO and ZF and ova (p<0.001).
In subfertile patient, both the penetration rate and penetration index were lowered in frozen ova (ZI; 62.3%, 1.3, ZF; 21.8%, 0.4) than those of fresh ova (74.8%, 1.8). There were significant correlation between the penetration rate and
penetration
index in ZI ova (p<0.05 and p<0.001, respectively).
In infertile patient, both the penetration rate and penetration index were ZI; 3.1%, 0.0, ZF; 0.0%, 0.0, respectively. There were significant correlation between the penetration rate and penetration index in I ova (p<0.05).
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