Hamster oocyte fertilizability after 4°C storage

The purpose of the present work was to study the feasibility of using hamster oocytes stored at 4°C in M-2 culture medium for 24 and 48 hours in the evaluation of human sperm fertilizability. A total of 1,394 oocytes were stored for 24 hours and 1,234 were stored for 48 hours. After the storage period all the ooctyes were stained with fluorescein diacetate, proving the physical integrity of the egg plasma membrane. Twenty-five and 22 semen samples were used to compare their ability to penetrate freshly ovulated and 24-and 48-hour-stored hamster oocytes. Freshly ovulated and 24-hour-stored oocytes were penetrated at percentages that in more than 95% of the cases showed no significant differences. The same experiments carried out with oocytes stored for 48 hours showed that in 75% of the cases no significant differences were found. The use of oocytes preserved at 4°C when large numbers of semen samples are to be tested for fertilizability is recommended.