Abstract:

【Objective】 This study was conducted to determine the effects of heat stress on the oxidate damage of organism(liver), genital system, oocytes and preimplantation embryos, and to observe oocytes’ and embryos’ subsequently developmental competence. 【Method】 TGSH and MDA in the oocytes, preimplatation embryos and several organs were determined by using total glutathione and malonaldehyde assay kit, respectively. The subsequently developmental competence of heat-stressed oocytes and embryos was determined. 【Result】 The subsequently developmental competence of the oocytes (6 h) and embryos (12 h) on day 1 to day 3 (before morula) in the mice heat-stressed at 35℃ for 6 h or 12 h decreased significantly. The TGSH content decreased and MDA output increased significantly in heat-stressed embryos on days 1, 2 and 3, but not in heat-stressed oocytes. However, nothing changed in embryos on days 4 and 5 of age cultured in vivo and the embryos on days 1 to 5 of age heat-stressed at 39℃ for 12 h cultured in vitro. The TGSH content increased and MDA output decreased significantly in liver and oviduct with the increased grading of heat stress and prolonged time, and in the ovary and uterus with 41℃ heat stress only.【Conclusion】The results demonstrate that the loss of developmental competence of early embryos is associated with oxidate damage of maternally heat-stressed enbryos before morula, but neither of maternally heat-stressed oocytes nor in vitro cultured 1 to 5d embryos.

Key words: heat stress, oocyte, preimplantation embryo, oxidative damage, developmental competence