Studies on bovine oocytes and ovarian tissues cryopreservation : fundamental and applied aspects

Tese de Doutoramento, Ciências Agrárias (Reprodução Animal), 26 de Junho de 2013, Universidade dos Açores.

Diversity of different sources of animal germ line has been acknowledged within the last few years, leading to a number of attempts for establishing a suitable protocol for preserving animal oocytes, gametes and recently extended to ovarian tissues and whole ovary preservation. Cryopreservation is considered an efficient procedure to achieve this desired target and become nowadays an integrated part of assisted reproductive techniques (Liu et al. 2009). Nevertheless, cryopreservation of immature oocytes at germinal vesicle stage (GV) and ovarian tissues, recently, have attracted significant interest from clinicians as well as researchers in biomedical and agricultural sciences (Ozmen and Al-Hassani 2010; Woods et al. 2004), considering both of them an optimal alternative strategy for germ line conservation over cryopreservation of mature oocytes and embryos (Li et al. 2007). Basically, there are two methods of cryopreservation: slow freezing and vitrification. Both methods have resulted in successful cryopreservation of oocytes and embryos (Kuleshova and Lopata 2002), however vitrification has become a viable and promising alternative technique rather than slow freezing due the success and simplicity of this technique especially when dealing with in vitro produced or micromanipulated embryos and oocytes (Pereira and Marques 2008). Therefore, the researcher’s attention has been attracted to the advantages of using vitrification technique, concluded by the perspective of Ozmen and Al-Hassani (2010) that vitrification will be the cryopreservation method of the future.

This Ph.D. research project (M3.1.3/F/003/2009) is supported by the Regional fund for Science and Tecnology funded by the Azorean Regional Government/Secretary of Science, Tecnology and Equipment.