Morphological, biochemical and functional studies to evaluate bovine oocyte vitrification

Area of Science:

• Reproductive biology
• Cryopreservation technologies
• Livestock science

Background:

• Oocyte cryopreservation is crucial for livestock breeding and conservation.
• Vitrification offers a promising alternative to slow freezing for oocyte preservation.
• Assessing the impact of vitrification on oocyte quality and developmental potential is essential.

Purpose of the Study:

• To evaluate the effects of vitrification and warming on bovine oocytes.
• To assess morphological, biochemical, and functional parameters at different recovery times.
• To determine the impact on oocyte competence for in vitro fertilization and embryo development.

Main Methods:

• Matured bovine oocytes were vitrified using the Cryotech® kit.
• Oocytes were incubated for 0, 3, or 21 hours post-warming.
• Morphology, viability, metaphase plate recovery, mitochondrial activity, ROS levels, and redox status were assessed.
• In vitro fertilization and embryo culture were performed to evaluate developmental competence.

Main Results:

• Vitrification did not affect oocyte viability or morphology.
• Metaphase plate recovery was optimal between 3 and 4 hours post-warming.
• Significant differences were observed in active mitochondria and reactive oxygen species (ROS) production between control and vitrified oocytes.
• A significant decrease in cleavage rate and embryo development was observed in vitrified-warmed oocytes.

Conclusions:

• The Cryotech® vitrification kit impacts oocyte metabolism, specifically mitochondrial activity and ROS production.
• Further improvements in oocyte vitrification protocols are necessary to maintain developmental competence.
• Vitrification, while preserving morphology, can compromise the functional capacity of bovine oocytes.