Developmental competence and glutathione content of maternally heat-stressed mouse oocytes and zygotes |
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| Authors: | Takaya MATSUZUKA Manabu OZAWA Miho HIRABAYASHI Atsuko USHITANI Yukio KANAI |
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| Institution: | Institute of Agriculture and Forestry, University of Tsukuba, Tsukuba-shi, Japan |
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| Abstract: | The loss of developmental competence and the glutathione (GSH) content of maternally heat‐stressed mouse oocytes and zygotes were determined. In experiment 1, zygotes were collected from female mice that were heat‐stressed at 35°C for 10 h after hCG injection (oocyte maturation stage), or for 12 h on Day 1 of pregnancy (zygote stage), followed by in vitro culture. To minimize the effects of heat stress on the fertilization process, heat‐stressed oocytes that were fertilized in vitro were also included in this experiment. In experiment 2, heat‐stressed oocytes and zygotes were assayed for GSH content. The application of heat stress to the oocytes resulted in a significant decrease in the percentage of zygotes that developed to morulae or blastocysts, both for naturally fertilized oocytes (56.9% for heat‐stressed vs 85.4% for control) or in vitro‐fertilized oocytes (54.5%vs 73.6%). In the heat‐stressed zygotes, the disruption of embryonic development was more drastic (24.3%vs 90.3%), with the majority of zygotes being arrested at the two‐cell stage. In contrast, the GSH content decreased significantly in heat‐stressed zygotes, but not in heat‐stressed oocytes. These results demonstrate that the loss of developmental competence of early embryos is associated with a decrease in the GSH content of maternally heat‐stressed zygotes, but not of maternally heat‐stressed oocytes. |
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| Keywords: | developmental competence glutathione content maternal heat stress oocytes zygotes |
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