Oócitos eqüinos: maturação in vitro e vitrificação

• Autor(a) principal: Leon, Priscila Marques Moura de
• Data de Publicação: 2008
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFPel - Guaiaca
• Texto Completo: http://repositorio.ufpel.edu.br/handle/ri/2518
• topic: Veterinária; Eqüinos; Cisteamina; OPS; SSV; Bloqueador de gelo; Cisteamine; Equines; Ice blocker; CNPQ::CIENCIAS AGRARIAS::MEDICINA VETERINARIA

In vitro maturation rates are low for equine oocytes in comparison with other species, although several media have been tested without satisfactory results. Vitrification of oocytes allows preservation of genetic material of relevant mares, the creation of genetic banks and the use of reproductive biotechniques. The first articles had the objective of evaluating the effect of cisteamine supplementation in the in vitro maturation medium for equine oocytes, through the analysis of membrane viability and nuclear maturation rates. The second article had the objective of evaluating the efficiency of vitrification using open pulled straws (OPS) and solid surface (SSV) using a synthetic ice blocker (Supercool X-1000 ) through the analysis of membrane viability and in vitro maturation rates. In article 1, oocytes were matured in vitro using three media: 1) medium supplemented with 50µM of cisteamine; 2) medium supplemented with 100µM of cisteamine; and 30 control. After maturation, denuded oocytes were stained and evaluated as far as nuclear maturation and membrane viability. The medium 2 presented higher (P = 0.0417) nuclear maturation rate (53.6%) than media 1 (42.5%) and 3 (43.2%), whereas no difference was observed for membrane viability across media (P < 0.05). In article 2, three experiments were conduced. In experiment 1, oocytes were allocated in a control group and at distinct vitrification media (OPS and SSV), exposed or not to X-1000. Higher maturation rates (P < 0.005) were observed for oocytes in the OPS with X- 1000 (20.3%) than for OPS without X-1000 (11.8%), SSV with X-1000 (11.4%) and SSV without X-1000 (12.1%). In experiment 2, a toxicity test was conducted, exposing oocytes vitrified in OPS and SSV to solutions including 1%, 0.1% and without X-1000. Higher maturation rates were observed for SSV with 0.1% X-1000 (61.4%) than for the other groups (P < 0.05). In experiment 3, vitrification solutions in OPS and SSV received inclusion of 1% and 0.1% X-1000, but no differences were observed in nuclear maturation and membrane viability (P > 0.05). In article 1, supplementation of in vitro maturation medium with 100µM cisteamine increased the nuclear maturation rate of equine ooccyte, without effect in membrane viability. In article 2, it was concluded that both OPS and SSV vitrification methods allow cryopreservation of immature equine oocytes, but the inclusion of X-1000 apparently reduces the toxicity of cryoprotectant solutions, whereas vitrification in OPS with X- 1000 showed better results.