O Instituto de Investigação e Tecnologia da Agronomia e Meio Ambiente (IITAA) desenvolve trabalho de investigação com o objetivo de perseguir estudos em diversas áreas, como a caracterização / previsão do clima insular e os efeitos das mudanças globais em comunidades do oceano para os to... Ler mais »
This study was undertaken to asses dissection/puncture combined technique for collecting large number of oocytes from bovine ovaries and to determine the effect of ovarian tissue cryopreservation on the oocytes capability to undergo in vitro maturation, fertilization and subsequent embryonic development.
Ovaries (n= 31) of slaughtered cows were cut into small fragments using a scalpel blade and the ovarian tissues were randomly assigned to cryopreserved by slow freezing and vitrification and non cryopreserved (fresh) group. Oocytes were collected from non-atretic follicles from fresh and post-thawing ovarian tissue by the puncture method. The advantage of this technique appeared through the good morphologically cumulus-oocyte complexes COCs recovery rate from fresh tissue (31.7±2.0 oocytes/ovary). However, the cryopreservation affect the post thawing total and good quality COCs recovery rate from slow freezing (26.6±2.0 and 23.5±2.3 oocytes/ovary, respectively) and vitrification group (21.7±1.1 and 17.6±1.8 oocyte/ovary, respectively). The maturation rate result in significant differences between the fresh tissue (94.1±1.1%) and the two cryopreservation groups. Moreover, the slow freezing group was significantly higher (80.1±1.3%) than the vitrification group (73.0±1.9%). No statistical differences were observed in the cleavage and the embryonic developmental rate between fresh tissue group and cryopreservation groups. Furthermore the number of embryos produced per animal was statistically higher for the fresh tissues as well as slow freezing and the vitrification group (34.4±1.4, 27.8±3.1 and 22.0±0.7, respectively). In conclusion, dissection method followed by puncture of bovine ovaries greatly maximizes the number of good quality oocytes, as well as the number of embryos obtained per animal. Ovarian tissue can be successfully cryopreserved by slow freezing and vitrification.
Segunda, 06 Dezembro, 2010