Abstract: ObjectiveTo study the effects of heat-ex posure on DCs in mesenteric lymph node of rats.MethodsImmunohistochemistry and image analysis were used to research the change of DCs in mesenteric lymph node of rats in different groups and at different time.ResultsAfter heat-exposed 2 hours merely,the amout of DCs in mesenteric lymph node of rats increased and reached the peak point at 8h,then went downward and came back to the initial value at 24h.The shape of DCs tended to be maturity,embracing the lymph cells;DCs of heat-acclimatized rats after heat-exposure though inceased either,the fluctuating of the value was not obvious;DCs of rats under the normal temperature were not changed.ConclusionHeat-exposure caused increased release of intestinal DCs,and made them come back to the mesenteric lymph node,the transformation of the immune system after heat stress was of some adaptability,viz DCs of rats released steadily after heat-acclimatization.