Cryopreservation of immature buffalo oocytes: Effects of cytochalasin B pretreatment on the efficiency of cryotop and solid surface vitrification methods

Abstract

The aim of the present study was to compare the efficiency of the solid surface (SSV), cryotop (CT) vitrification methods and cytochalasin B (CB) pretreatment for cryopreservation of immature buffalo oocytes. Cumulus-oocyte complexes (COCs) were placed for 1 min in TCM199 containing 10% dimethylsulfoxide (DMSO), 10% ethylene glycol (EG), and 20% fetal bovine serum, and then transferred for 30 s to base medium containing 20% DMSO, 20% EG and 0.5 mol/L sucrose. CB pretreated ((+)CB) or non-pretreated ((-)CB) COCs were vitrified either by SSV or CT. Surviving vitrified COCs were selected for in vitro maturation (IVM) and in vitro fertilization (IVF). The rate of viable oocytes after vitrification in CT groups (82%) was significantly lower (P < 0.05) than that in a fresh control group (100%), but significantly higher (P < 0.05) than those in SSV groups (71-72%). Among vitrified groups, the highest maturation rate was obtained in the CT (-)CB group (32%). After IVF, the cleavage and blastocyst formation rates were similar among vitrified groups but significantly lower than those of the control group. In conclusion, a higher survival rate of oocytes after vitrification and IVM was obtained in the CT group compared with that in the SSV group, indicating the superiority of the CT method. Pretreatment with CB did not increase the viability, maturation or embryo development of vitrified oocytes.

In Vitro Maturation and Fertilization of Cryopreserved Oocytes of Egyptian Buffaloes.

“…Method of oocyte cryopreservation affected viability of oocytes and the success of cryopreservation is based on procedures that minimize the formation of intra-cellular ice crystals as affected by cryodevice and the surrounding cryoprotectants. In buffaloes, the cryotop was better than the solid surface vitrification method in term of viable immture oocyte yield after cryopreservation (Liang et al, 2012). In bovine, Hajarian et al (2011) mentioned that vitrification of immature bovine oocytes with the cryotop method resulted in higher survival and nuclear maturation rates.…”

“…This was in association with remarkable effects negatively on viability and quality of buffalo oocytes during cryopreservation. Liang et al (2012) found that cryopreservation method affected in vitro maturation of buffalo oocytes. The cryotop was better than the solid surface vitrification method in term of in vitro maturation.…”

Effect of vitrification procedures on the subsequent development of in vitro matured swamp buffalo oocytes following in vitro fertilization

“…Vitrification by CT results in excellent survival and developmental rates of human and bovine oocytes (Kuwayama et al., ). Swamp buffalo oocytes at the metaphase of the second meiotic division (MII) have been successfully vitrified by CT, retaining the capability to enter the blastocyst stage after parthenogenetic activation, nuclear transfer, and IVF (Attanasio et al., ; Liang et al., 2012b; Muenthaisong, Laowtammathron, Ketudat‐Cairns, Parnpai, & Hochi, ). SSV applies a dry metal surface cooled by LN 2 to vitrify oocytes in 1–2 μl microdrops (Dinnyés et al., ).…”

Effects of polyethylene glycol and a synthetic ice blocker during vitrification of immature porcine oocytes on survival and subsequent embryo development

“…The exact mechanism behind this phenomenon remains to be elucidated. In the present study, instead of the microdrop procedure, we used Cryotop as the carrier for vitrification because it is known to provide excellent cooling/warming rates (Liu et al ; Spripunya et al ; Liang et al ; Wu et al ). Nevertheless, the results achieved by the use of Cryotop in the present study were not improved compared with those of our previous reports using microdrops.…”