Study On Qick Vitrification Cryopreservation Of Buffalo Oocytes

As the rapid development of embryo engineering, the quantity of oocytes has been a restricted problem of in-vitro fertilization (IVF), nuclear transfer (NT) and embryo transfer (ET). The cryopreservation of oocytes can effectively resolve that problem. This research adopted buffalo to study the theory of cryopreservation and structure of oocytes, and discussed the the effects of frozen carrier, cryoprotectant, DMSO, serum, cumulus cells, different maturation phases of oocytes and thaw on vitrification cryopreservation; in order to find an effective cryopreservation method for buffalo oocytes, and get over the limited source of bovine ovaries. The results are as followings:1. The effect of frozen carrier on vitrification cryopreservation. The bovine oocytes IVM for 18h were adopted, four materials such as A (0.25ml plastic straw), B (glass straw 1), C (glass straw 2), D (thinpoint of needle) were used as frozen carrier. The oocytes were pretreated in with VS₁ with 10%DMSO+20%FBS for 30s, and then in VS₂with 20%DMSO+20%FBS for 20s, and then they were cryopreserved follwed by two-step thaw; after that, the oocytes were maturated and parthenogenetically activated, the recovery rate (RR), percentage of oocytes with normal modality (PM), maturation rate (MR), cleavage rate to 2-8-cell (CR). The control were matutated and parthenogenetically activated without cryopreservation. As a result, the MR, 2-4-cell rate and 8-cell rate (68.3%, 51.7% ,36.1% )were significantly higher than those in other groups, it indicated that cryopreservation brings damage to oocytes. The PM, MR, 2-4-cell rate and 8-cell rate in group A (87.2%, 43.9%, 34.1%, 21.9%) were significantly lower than those in group B (93.8%, 51.7 %, 40.0%, 28.3%) , group C (94.7%, 51.9%, 40.7%,27.8%) , group D (94.4%, 55.9 %,41.2%, 29.4% ) . the results showed group A was not suitable to be carrier, Group D had high MR, 2-4-cell rate and 8-cell rate, but the RR (69.2% ) was significantly lower than group A (87.0 % ) , group B (94.1 % ) and group C(91.9%), the low RR lead it is not suitable to be carrier. The group C and D has a RR of (94.1% Vs 91.9% ) , PM of (93.8% Vs94.7% ) , MR of (51.7% Vs 51.9%) , 2-4-cell CR of (40.0% Vs 40.7%) ,8-cellCRof (28.3% Vs 27.8%) which was higher than those in group C and D, and there was no difference between group B and C. In conclusion, B and C is suitable to be frozen carrier.2. The effect of DMSO as penetrative cryoprotectant cryopreservation. The IVM oocytes were cryopreserved by vitrificational fluild (group C) with or without DMSO. After thaw, the PM in...