Doctor of Philosophy (PhD)
Biomedical and Veterinary Medical Sciences - Veterinary Clinical Sciences
Semen cryopreservation has allowed the establishment of genome banks and the large scale propagation of species. The development of simple techniques to cryopreserve semen or alternatives to efficiently use cryopreserved semen from males of valuable genetics that have become infertile will permit continuous propagation of the genetics from these males and may serve as a model for preservation and propagation of endangered species. Sperm cryopreservation without cryoprotectants is a simple process, and offspring have been produced following intracytoplasmic sperm injection (ICSI); however the ability of frozen-thawed sperm refrozen without the addition of cryoprotectants to activate oocytes following ICSI was unknown. In the series of experiments performed, bull and stallion frozen-thawed sperm refrozen without the addition of cryoprotectants was used to activate intra- and interspecies oocyte following ICSI. Additionally, equine cumulus-oocyte complexes (COCs) glucose metabolism during in vitro maturation was evaluated. The first experiment demonstrated that bull and stallion frozen-thawed sperm refrozen without the addition of cryoprotectants had their plasma membrane damaged; however the DNA was unaffected. The second experiment demonstrated that bull and stallion frozen-thawed sperm refrozen without the addition of cryoprotectants had the ability to activate bovine oocytes following intracytoplasmic sperm injection; although at a lower rate compared to frozen-thawed sperm. The third experiment demonstrated that frozen-thawed stallion sperm refrozen without the addition of cryoprotectants was unable to activate equine oocytes. The exact reason for this failure could not be explained from the experiment; however COC metabolism during in vitro maturation impacts embryo activation/development and required further investigation. The fourth experiment demonstrated that equine COCs consume and metabolize glucose through glycolysis during in vitro maturation; however, results from this experiment were unable to explain the failure of refrozen stallion sperm to activate equine oocytes. To our knowledge, this is the first report of the use of bull or stallion frozen-thawed sperm refrozen without the addition of cryoprotectants to activate oocytes following ICSI. Furthermore, this is also the first report of equine COCs glucose metabolism during in vitro maturation.
Document Availability at the Time of Submission
Release the entire work immediately for access worldwide.
Len Yin, Jose, "The Ability of Bull and Stallion Thawed Spermatozoa Refrozen without Cryoprotectants to Activate Intra- and Interspecies Oocytes" (2016). LSU Doctoral Dissertations. 2508.