Oócito do felino doméstico: Estratégias e desafios na MIV e na criopreservação
Leal, Gabriela RVasconcelos, Erlandia MMaia, Ana Lúcia R. SGuimarães, Mariana P. POliveira, Thais AOliveira, Thais A
The oocyte plays a pivotal role in the development of reproductive biotechnologies, as its developmental competence directly impacts embryo production. This review compiled the main findings on the cat oocyte intrinsic characteristics, the strategies used to optimize oocyte IVM, and the challenges and approaches employed in the oocyte cryopreservation protocols. Cat oocytes present a great lipid content, and the ones with a dark, finely granulated cytoplasm and multiple layers of cumulus cells are classified as top-quality, whereas those with light cytoplasm are associated with lower fertilization rates. Around 40- 60% of oocytes submitted to IVM achieve the MII stage. Generally, they present an impaired glucose metabolism compared to their in vivo counterparts and can respond to cAMP modulators differently compared to other species. Moreover, they present a lipid accumulation during IVM, and lipid modulators can reduce their accumulation and improve cryosurvival, however, they also impact oxidative metabolism. Ascorbic acid, L-cysteine, L-carnitine, and resveratrol have been added before or during IVM with positive effects on oocyte oxidative parameters following IVM and on cryopreservation. Different strategies have been used to optimize oocytes' cryotolerance and improve survival rates, like delipidation before vitrification and the addition of the antifreeze protein I and extracellular vesicles in the cryopreservation solutions. The understanding of cat oocyte singularities beyond its behavior under in vitro conditions is essential to the development of strategies that improve IVM and the outcomes after cryopreservation.(AU)
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