Abstract: The present study was conducted to investigate the stress response of nuclear or cytoplasmic components to heat shock, and the detrimental effects of heat shock on expression of zygotic genes stage, cell apoptosis and in vitro development of bovine embryos. The parthenogenetic embryos were incubated at 38.5 or 41 ℃ for 7 h, respectively; then the nuclei of embryos cultured at 41 ℃ were transferred into cytoplasts enucleated at 38.5 ℃ to construct heat shock nucleinormal cytoplasm embryos (HN embryos) and 38.5 ℃ nuclei were transferred into 41 ℃ cytoplasts to construct heat shock cytoplasm-normal nuclei embryos (HC embryos). The development rate of nuclei-cytoplasm exchange embryos, expression of zygotic activated genes and apoptosis of embryo cells were detected. In vitro culture showed that blastocyst formation rate for HC embryos decreased significantly compared to parthenogenetic embryos in control and HN embryos.Incomplete activation of zygotic genes was observed in nuclear exchange embryos, especially in HC embryos. It suggested that heat shock might disrupt some cytoplasmic factors required for zygotic gene activation. Apoptosis induced by heat shock was observed in both HN and HC blastocysts and the incidence of apoptosis in HC blastocysts was significantly higher than that in HN embryos. These results suggested that: although heat shock injuries exist in both nuclear and cytoplasmic components, cytoplasmic component is more susceptible to heat shock than nuclear component.