Degree
Doctor of Philosophy (PhD)
Department
Veterinary Biomedical and Clinical Sciences
Document Type
Dissertation
Abstract
Assisted reproduction technology and the use of specialized laboratories have increased in the horse breeding industry over the last decade. This expansion has highlighted the inability to routinely cryopreserve oocytes and preserve female genetics. Oocyte vitrification, a cryopreservation process, continues to be characterized as an experimental procedure in horses. The goal of this dissertation was to evaluate the viability, developmental competence, and nuclear structures of cryopreserved equine oocytes to illuminate potential areas of improvement in the vitrification process. Oocytes were collected from abattoir derived ovaries and exposed to either varying lengths of in vitro maturation (IVM) or pretreated with a microtubule stabilizing agent, paclitaxel, prior to vitrification. Extended IVM culture prior to vitrification resulted in higher viability post-warming but did not improve overall developmental competence of oocytes injected with sperm upon warming. Cell cleavage rates were similar among all IVM culture periods but resulted in few blastocysts. Vitrified oocytes pretreated with paclitaxel presented significantly higher normal chromosome arrangements (p > 0.05) compared to standard vitrification but did not differ in microtubule distribution. Nonvitrified paclitaxel pretreated oocytes experienced decreased viability following IVM compared to controls. Oocytes were then collected by transvaginal aspiration (TVA) and vitrified before or after IVM culture. Mature oocytes were injected with sperm and evaluated for developmental competence. Oocytes vitrified prior to IVM had lower maturation rates xii compared to controls and oocytes vitrified following IVM. Vitrification following IVM resulted in lower cell cleavage rates compared to vitrification pre-IVM and controls. TVA collected oocytes were vitrified prior to IVM culture containing antioxidant, resveratrol, and mature oocytes were injected with sperm. Resveratrol did not improve overall developmental competence in vitrified equine oocytes. These oocytes exhibited similar maturation rates following IVM but had reduced cell cleavage and blastocyst rates compared to controls. Further studies evaluating concentration and exposure time of resveratrol and paclitaxel could improve developmental potential in equine oocytes following vitrification.
Date
10-31-2024
Recommended Citation
Adams, Tricia, "Evaluating Viability, Developmental Competence, and Chromatin Configurations of Cryopreserved Equine Oocytes" (2024). LSU Doctoral Dissertations. 6641.
https://repository.lsu.edu/gradschool_dissertations/6641
Committee Chair
Carlos Pinto
Included in
Large or Food Animal and Equine Medicine Commons, Reproductive and Urinary Physiology Commons, Veterinary Physiology Commons