VITRIFICACIÓN OF OOCYTES SHEEP: ULTRASTRUCTURAL EVALUATION AND CITOFISIOLÓGICA.Author:
DIAZ CORUJO ANA ROCÍO.
Year:
2006.
University:
LEÓN [
www.unileon.es].
Place of defense: FACULTAD DE VETERINARIA.
Place of preparation: FACULTAD DE VETERINARIA.
Summary: The cryopreservation of eggs offers many advantages with regard to the freezing of embryos. However, this is very complex and specialized cells with characteristics that hinder their cryopreservation, as its greatest volume and certain properties of the membrane. In this paper we used vitrification to criopreservar oocytes, the method characterized by high rates of cooling, the use of high concentrations of crioprotector, and very small volumes of media. The vitrification was done by direct immersion in liquid nitrogen and using the VitMaster (up to -210 ° C), and as support for the pajuelas SOPS oocytes. It vitrificaron oocytes in VG (VG-VITRIF) and mature state (MIV-VITRIF) from large and small follicles. The effects of vitrification identified studying the ultrastructure and the state citofisiológico. Both vitrified oocytes in VG, as a mature presented very low percentages of nuclear maturation. When vitrification was with the VitMaster, the major results were obtained in mature oocytes vitridicados state. In all other cases, there was no significant difference. The microtubules of the spindle meiótico experienced great damage as a result of the vitrification oocytes in VG and mature state mainly due to intense despolimerización. In the two states of maturation, microtubules experienced further damage to the chromosomes of the plate metafásica. The vitrification also damaged in microtubule-actin, at the band actin and projections zonal, especially important in oocytes immature oocytes already involved in the process of maturing. However, the damage was less than in tubulin, and that about 50% of oocytes show actin normal. The vitrified oocytes in the mature state showed greater damage on the distribution and morphology of cortical granules compared with vitrified oocytes in VG and also mitochondria. These damages were voiced mainly cortical level. Both the vitrified oocytes in VG as in mature state, had compromised the ability to synthesize ATP par. In vitrified oocytes in the mature state, the vitrification with SOPS and VitMaster caused minor damage in the band of actin and microtubule spindle meiótico. However, mitochondria and overall glucose metabolism were more fortunate when vitrification was conducted with pajuelas SOPS and direct immersion in liquid nitrogen.
