Effect of bovine oocyte vitrification with EGTA and post-warming recovery with resveratrol on meiotic spindle, mitochondrial function, reactive oxygen species, and developmental competence.

The present study aimed to determine the effects of the addition of EGTA to vitrification solutions and a post-warming recovery period supplemented with 1 μM resveratrol on meiotic spindle integrity, mitochondrial activity, ATP content, reactive oxygen species (ROS) levels, and developmental potential of partially denuded, vitrified-warmed bovine oocytes. Results of microtubule distribution and chromosomal arrangement indicated that resveratrol supplementation, irrespective to EGTA addition, reduced the incidence of abnormal meiotic spindles to similar levels of the control group. Mitochondrial membrane potential was similar in all groups, but ATP content was negatively affected by the vitrification-warming procedure and failed to recover after 4 h of post-warming culture.

Recovery of spindle morphology and mitochondrial function through extended culture after vitrification-warming of bovine oocytes.

The present study aimed to determine the effects of vitrification on the meiotic spindle and mitochondrial function of bovine oocytes submitted to different times of post-warming culture. Partially denuded cumulus-oocyte complexes were vitrified at different maturation times (18-, 20-, and 24-h) using a two-step cryoprotectant addition protocol and submitted to 6-, 4-, or 0-h of post-warming extended culture in maturation medium. Microtubule configuration and chromosomal arrangement were analyzed after 0- and 6-h of extended culture, whereas mitochondrial membrane potential and ATP content were measured at 0-, 4-, and 6-h of post-warming recovery.

Evaluation of Seasonal Heat Stress on Transcriptomic Profiles and Global DNA Methylation of Bovine Oocytes.

Heat stress affects oocyte developmental competence and is a major cause of reduced fertility in heat stressed cattle. Negative effects of heat stress on the oocyte have been observed at morphological, biochemical and developmental levels. However, the mechanisms by which heat stress affects the oocyte at the transcriptional and epigenetic levels remain to be further elucidated.

Pregnancy Rates Following Low-Temperature Storage of Large Equine Embryos Before Vitrification.

Satisfactory pregnancy rates can now be achieved following the cryopreservation of large equine embryos. Nonetheless, its wide application might be limited by the fact that the cryopreservation of large equine embryos requires a specialized micromanipulation equipment and micromanipulation/vitrification skills. Alternatives should be developed to increase its utilization and widespread application in the commercial equine industry.