The objectives of this study were to investigate whether blastocoel collapse before vitrification induced by laser improves the cryo-survivability of buffalo in-vitro-fertilized (IVF) blastocysts and whether laser assisted hatching (LAH) promotes hatchability of fresh and frozen-thawed IVF blastocysts. The expanded blastocysts were harvested on Days 6-9 and randomly allocated into five groups as follows: (1) blastocysts were vitrified and thawed without any treatment; (2) blastocysts were vitrified after 15-20 μm zona pellucida (ZP) thinning opposite to the inner cell mass, and blastocoels were also blotted in order to outflow the blastocoelic fluid before vitrification; (3) ZP thinning was made immediately after thawing; (4) fresh blastocysts underwent LAH; and (5) as a control, fresh blastocysts without treatment. Results of the present study showed that the cryosurvival rates of vitrified Day 8 and Day 9 blastocysts in Group 2 were significantly (P < 0.01) higher in Group 2 than Group 1. The hatching rates of Day 8 and Day 9 blastocysts in Group 2 and Group 3 were also significantly (P < 0.01) higher compared with Group 1. Moreover, the hatching rate of Day 9 blastocysts in Group 4 was notably (P < 0.05) higher than Group 5. In conclusion, LAH promotes the hatching rates of Day 9 fresh and Days 8-9 vitrified blastocysts, and artificial blastocoel collapse before vitrification improves the cryosurvival rate of Days 8-9 IVF buffalo blastocysts.
Keywords: Assisted blastocoel collapse; Blastocyst; Buffalo; Laser assisted hatching; Vitrification.
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