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 assess 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 andsubsequent embryonic development. Ovaries (n = 31) of slaughtered cows were cut into small fragments using a scalpel bladeand the ovarian tissues were randomly assigned to cryopreserved by slow freezing and vitrificationand non cryopreserved (fresh) groups. Oocytes were collected from non-atreticfollicles from fresh and post-thawing ovarian tissue by the puncture method. The advantageof this technique appeared through morphologically good quality cumulus–oocytecomplex (COC) recovery rate from fresh tissue (31.7±2.0 oocytes/ovary). However, thecryopreservation affected the post thawing total and good quality COC recovery rates from slow freezing (26.6±2.0 and 23.5±2.3 oocytes/ovary, respectively) and vitrificationgroups (21.7±1.1 and 17.6±1.8 oocyte/ovary, respectively). The maturation rate resultedin significant differences between the fresh tissue (94.1±1.1%) and the two cryopreservationgroups. Moreover, this rate was significantly higher in the slow freezing group (80.1±1.3%) than in the vitrification group (73.0±1.9%). No statistical differences were observed in the cleavage and the embryonic developmental rates between fresh tissuegroup and cryopreservation groups. Furthermore the number of embryos produced peranimal was statistically higher for fresh tissues than for slow freezing and the vitrification groups (34.4±1.4, 27.8±3.1 and 22.0±0.7, respectively). In conclusion, dissectionmethod followed by puncture of bovine ovaries greatly maximizes the number of good quality oocytes recovered, as well as the number of embryos obtained per animal. Ovarian tissue can be successfully cryopreserved by slow freezing and vitrification.
Domingo, 13 Fevereiro, 2011