THREE-DIMENSIONAL SCAFFOLDS FOR IN VITRO CULTURE OF FELINE OOCYTES.

The cumulus-denuded oocytes (CDOs) are not commonly involved in the assisted reproductive techniques (ARTs), as the absence of their surrounding cumulus cells negatively affects their maturational and developmental competence in vitro. In some cases these gametes could represent an interesting option for widening the germinal pool of high value individuals with very precious genetic material and could be the only genetic source when the selected cumulus-oocyte complexes (COCs, grade I) are cryopreserved. Therefore, enriched culture conditions to improve the CDOs in vitro full competence should be adopted. The innovative three-dimensional (3D) scaffolds, derived from the bioengineering and nanotechnology research, ensure the optimal culture conditions to maintain the cells physiological conformation and behavior as in the in vivo environment. In this thesis, the association of 3D barium alginate microcapsules with competent COCs was used to improve the in vitro performances of domestic cat CDOs. The results showed that the 3D BA microcapsules are suitable systems for the in vitro culture of feline oocytes, as their viability and in vitro maturation rates and embryonic development were similar to those obtain in the traditional 2D system. The enriched co-culture condition did not improve the in vitro competence of CDOs, as their full maturational (TI-MII) rates and late embryo stages (morulae and blastocysts) were similar to those of the CDOs cultured separately or to those of the COCs control. However, the presence of CDOs in the co-culture with COCs improved significantly the in vitro developmental rates of the high competence oocytes, presumably for the paracrine action of some specific oocyte-secreted factors (OSFs). A better knowledge of the expression profiles of potential oocyte quality markers, as the OSFs, and how they could differ from COCs and CDOs in the 3D and 2D systems could help the design of the optimal enriched culture conditions for the domestic cat low competence oocytes.