Semester of Graduation

Fall 2025

Degree

Master of Science (MS)

Department

Animal Science

Document Type

Thesis

Abstract

Oocyte vitrification success is highly dependent on cryoprotectant agent (CPA) choice as well as possible additives that could help preserve mitochondrial membrane potential (mMP), reactive oxygen species (ROS) production, and calcium homeostasis within the cell. It is a delicate balance between levels needed for proper oocyte function and activation and levels needed to induce apoptotic pathways. The results of oocyte cryopreservation determine the eventual oocyte viability and subsequent fertilization and embryo development.

In this study potential permeating cryoprotectant combinations were explored such as ethylene glycol (EG) and propylene glycol (PG) or EG in combination with dimethyl sulfoxide (DMSO). Also, the effects of mitochondrial permeability transition pore (mPTP) inhibitor cyclosporin a (CsA) and endoplasmic reticulum (ER) stress inhibitor tauroursodeoxycholic acid (TUDCA) were observed. When determining the effects of both CsA and TUDCA, the timing of application was also considered; control (no treatment), post-only treatment, or pre- and post-treatment. Mitochondrial membrane potential (mMP), Reactive oxygen species (ROS) production, and intracellular free calcium ratios were used in the statistical analysis of this experiment.

Results of the first experiment that evaluated CPA combinations and CsA addition to the media concluded that mMP was not capable of being rescued when CsA was treated post-only and could cause membrane depolarization. ROS production was also increased in those treated with CsA. The second experiment, testing CPA combinations and TUDCA revealed that mMP was preserved in oocytes treated with EG + DMSO as well as those treated with TUDCA pre + post vitrification. More notably, ROS production was observed to be lower in oocytes treated with TUDCA both post-only and pre- and post-vitrification. While few differences in free calcium patterns were observed across both experiments, the calcium oscillation peaks, and peak frequency behavior did not align with values reported in literature. This could possibly be due to parthenogenic activation protocols used before imaging or due to the vitrification process itself.

Date

8-26-2025

Committee Chair

Bondioli, Kenneth

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Available for download on Wednesday, August 26, 2026

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