Transporte simulado de oócitos bovinos em meio de maturação por diferentes períodos de tempo sem controle da atmosfera gasosa

Abstract

The transport of the oocytes until the laboratory is a determining factor that has limited the commercial diffusion of the Production in vitro embryo technique (PIVE). For this reason, the use of a means of transport-maturation to provide greater viability to the oocytes during the transport is fundamental. The objective of this study was to evaluate the viability of the simulated transport of the bovine oocytes in chemically defined medium, by different periods of time without the gaseous atmosphere control, and the need for the addition of hormones in this medium. Immature bovine oocytes (n=989) obtained from bovine ovaries of cows slaughtered in a refrigerator, were selected and randomly distributed in 2 experiments. In experiment I, 649 oocytes were distributed into 5 groups. In the control group (0h), the oocytes were borne during 24h by means of maturation, in a CO2 incubator at 38,5ºC. The oocytes were transported in an incubator portable without gaseous atmosphere control at 38,5°C for 3, 6, 9 and 12h. The oocytes of experimental groups completed the maturation under the same conditions of the group 0h. In experiment II, 340 oocytes were distributed into 5 groups. In the control group (0h), the oocytes were matured during the same conditions of the group 0h of the experiment I. The experimental groups, the oocytes were transported under the same conditions of the experiment I, however the means of transport-maturation was supplemented or not with hormones, and the transport occurred in 3h (with and without hormones) and 6h (with and without hormones). The oocytes of experimental groups completed the maturation under the same conditions of the of the group 0h. The fertilization was performed in Talp-Stock by 18 to 22h and growing by 7 days in SOF medium. In experiment I, the rates of cleavage were statistically similar (p>0,05) to the groups 0h (64,9%) and 3h (56,2%), although there was a reduction in these rates in the groups 6h (45,8%), 9h (47,1%) and 12h (44,0%), which were similar among themselves. The production of blastocysts in experiment I, was not statistically different (p>0,05) for the groups 0h (38,0%) and 3h (32,3%), but there was a reduction in these rates in groups 6h (27,3%), 9h (24,8%) and 12h (18,9%), however, the rates of blastocysts are similar among the groups 3h, 6h and 9h. In experiment II, the rates of cleavage were statistically similar (p>0,05) to the groups 0h (71,4%) and 3h with hormones (70,3%), but there was a reduction in these rates in groups 3h without hormones (64,8%), 6h with (56,0%) and without (54,1%) hormones, which were different among themselves. The production of blastocysts in experiment II, was statistically similar (p>0.05) for the groups 0h (46,1%) and 3h with hormones (45,8%), but there was a reduction in these rates in groups 3h without hormones (41,1%), 6h with (35,5%) and without (33,5%) hormones, which were different among themselves. These results indicate the possibility of the transport of bovine oocytes, in chemically defined medium, using incubator portable, without gaseous atmosphere control, at 38,5ºC, for the period of up to 9h, and that the addition of hormones in this medium may increase the rates of blastocysts.