This study was carried out to set up the ovum bank for ovum donation and to determine the best freezing method for human immature oocytes.
Human immature follicular oocytes were cryopreserved by slow freezing and rapid thawing method. Immature follicular oocytes were treated by propanediol (PROH) solution by 2 and 4 step method in protocols A & B, respectively. In protocol C,
immature
oocytes were exposed to sucrose prior to treatment of PROH by 4 step method. We compared survival rate, maturation rate, and fertilization rate of immature oocytes among three protocols. @ES Results were as follows.
@EN 1. Oocytes treated by the protocol C showed the highest survival rate (70.3%) and maturation rate (34.6%) after thawing.
2. Survival rate of oocytes treated by the protocol C was significantly higher than that of the protocol B after thawing (p<0.05).
In conclusion, treatment of oocytes with sucrose prior to expose PROH was the best freezing method. Sucrose may have reduced the toxic effect of cryoprotectant to oocytes. We failed to induce fertilization of oocytes, which were treated by any
protocols, by conventional insemination method, but obtained 28.8% fertilization rate by using partial zona dissection (PZD) method. This result suggests that micromanipulation (PZD) of the thawed oocytes before insemination will improve the
fertilization rate.
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