UBC Theses and Dissertations
Cryopreservation and transplantation of gonadal tissue for genetic conservation and biological research in avian species Liu, Jianan
Avian researchers and the poultry industry have experienced a massive loss of genetic resources due to the high cost of maintaining live flocks. Cryobanking of germplasm is economical and ensures long-term availability of genetic resources. Cryopreservation and transplantation of avian gonadal tissue allow effective preservation and recovery of female germplasm and provide an alternative to semen cryobanking. A vitrification protocol including dimethyl sulphoxide, ethylene glycol and sucrose as cryoprotective agents and the use of acupuncture needles to facilitate tissue handling has been successful in preserving Japanese quail ovarian tissue. Its effectiveness in preserving testicular tissue is unknown and an efficient storage system is needed. The vitrification protocol was first adapted to a 0.5-ml straw system and used to cryopreserve quail ovarian tissue, which showed no significant impairment of viability or vascularization compared to fresh tissue after in ovo culture. This system was then replaced by a simpler 2-ml straw system and applied to quail testicular and ovarian tissue. Normal morphology of testicular tissue was observed after in ovo culture and live offspring were produced by intramagnal insemination of the extrusion retrieved from allotransplants of cryopreserved testicular tissue. Donor-derived offspring were also efficiently produced from cryopreserved and allotransplanted ovarian tissue. Gonadal transplantation is critical to functional recovery of cryopreserved tissue but can be limited by tissue rejection. Donor thymic tissue was implanted into recipient embryos and gonadal tissue from the same donor was transplanted ectopically to the recipient after hatching. Transplant viability and histology was examined. Thymic implantation may improve survival of the allogeneic gonadal transplants in chickens but not the xenotransplants from quail to chickens. Investigations of avian ovarian transplantation have led to intriguing additional observations. Donor-derived offspring were produced from transplanted adult quail ovarian tissue, although delayed age at first egg and reduced reproductive longevity were observed with the transplants. As well, offspring with chimeric plumage coloration were produced from cryopreserved and transplanted chicken ovarian tissue, indicating chimeric folliculogenesis. This dissertation provides a model of cryobanking avian gonadal tissue using a simple vitrification method, and suggests future directions in improving transplantation tolerance and using gonadal transplantation in avian research.
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