Effect of Different Duration on Oocytes Maturation in Vitro of Domestic Cat

Abstract: In vitro maturation (IVM) of oocyte is a technoly which simulates the inviorment of the follicular with gonadotropin-releaseing hormone (GnRH) and steroid hormone and indures the immatured oocyte to matured oocyte. It is a basical technology of assisted reproductive technology (ART). In vitro fertilization, parthenogenetic activation of oocyte, nuclear transfer and so on, are basical on IVM. There are many factors which influence the efficiency of maturation in vitro, and duration is one of the factors. On the one hand, duration of IVM is too short to cause the maturation of oocyte nuclear and/or cytoplasm, and to cause high cleavage rate, morula rate, blastocyst rate, fuse rate, and so on. On the other hand, if duration of IVM is too long, it would lead to oocyte degradation and the phenomenon such us low cleavage rate and so on. In this study, we compared the effect of different maturation duration on oocytes maturation in vitro of domestic cat in order to select the best maturation duration. Maturation rate, degeneration rate and artifical activation were used as maturation criterion. Moreover, CGs staining was used to male sure the oplasm maturation of the differt maturation duration oocytes. This study got following resultes.1 The rate of nuclear maturation in the 43h group was significantly higher than the others (66.89% vs 31.51%, 48.00%, 45.45%, 47.06%, P<0.01). The rate of nuclear maturation in the 24h group was significantly lower than the others (31.51% vs 48.00%, 45.45%, 47.06%, 66.89%, P<0.01), but there was no significant differences of the rate of nuclear maturation among other three groups(48.00%, 45.45% vs 47.06%, P>0.05). In addition, the rate of degeneration in the 43h group was also significantly higher than the others (22.30% vs 5.48%, 3.00%, 1.52%, 3.92%, P<0.01).Conclusion The results showed that the optimal nuclear maturation of feline oocytes appeared following the duration from 28 to 36h by IVM.2 The cleave rate of activated oocytes in the 32h group was significantly higher than the 28h group (60.42% vs 43.16%, 0.01<P<0.05), but there was no significant difference between the 32h group and the 36h group (60.42% vs 50.00%, P>0.05). After activation, there was no oocyte which developed to blastula. The rate of morula in the 32h group was highest, but there was no significant differences among 28h, 32h, 36h(7.37%, 15.63% vs 10.78%, P>0.05). The results showed that the optimal maturation duration of feline oocytes was 32h. 3 CGs were found throughout the oocyte cytoplasm. The CGFD didn’t appear in oocytes of domestic cat. There were more CGs located in the cortex of the oocytes which were matured 32h than the other groups. CGs decreased in oocytes matured 36h and 43h. The resultes showed that oocytes matured 32h got ready to be sitimulated, and after 32h the oocytes were degraded. So, 32h was the best maturation duration of domestic cat oocytes IVM…
Key words: domestic cat; oocyte; duration of IVM; parthenogenetic activation; cortical granules

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