The purpose of this study was to investigate the effects of estradiol(E)and progesterone(P)on mastocyte distribution in the uterus of ovariectomized rats.Thirty-five adult female rats were divided randomly into seven groups:one sham operated control group(SHAM);one ovariectomized group(OVX);three ovariectomized plus E treatment groups(OVX+E 20,100,or 500 μg/kg body weight·d);and two ovariectomized plus P groups(OVX+P 2 or 10 mg/kg body weight·d).Seven days after treatment,the contents of estradiol and progesterone in serum were detected by radioimmunoassay,and mastocytes in the uterus were stained by toluidine blue staining.Results were as following:① Compared to ovariectomized rat,the concent ration of estradiol in serum increased by 97.13 % in OVX+E 20(P<0.05),204.84 % in OVX+E 100(P<0.05),and 936.45 % in OVX + E 500 group(P<0.05);the progesterone concent ration increased by 77.25 % in OVX+P 2(P<0.05)and 235.25 %in OVX+P 10 group(P<0.05).② Compared to ovariectomized rat,the number of mast cells in uteri decreased by 32.65% in OVX+E 20,64.50 % in OVX+E 100(P<0.05),74.49 % in OVX+E 500(P<0.05)and 70.67 % in OVX+P 10 groups(P<0.05).However,the number of mast cells increased by 66.73% in OVX+P 2 group(P<0.05)compared with OVX.The trend of mast cells number in the rat uterus was decreased gradually with the increase of estrogen or progesterone concent ration.The number of mast cells in ovariectomized rat uterus was affected by estrogen or progesterone.These results demonstrated that estrogen or progesterone directly affected the number of mast cells in the uterus of rat. The purpose of this study was to investigate the effects of estradiol (E) and progesterone (P) on mastocyte distribution in the uterus of ovariectomized rats. Thirty-five adult female rats were divided into seven groups: one sham operated control group (SHAM ; three ovariectomized plus E treatment groups (OVX + E 20,100, or 500 μg / kg body weight · d); and two ovariectomized plus P groups (OVX + P 2 or 10 mg / kg body weight · D). Se days days treatment, the contents of estradiol and progesterone in serum were detected by radioimmunoassay, and mastocytes in the uterus were stained by toluidine blue staining. Results were as follows: ① Compared to ovariectomized rat, the concent ration of estradiol in the serum increased by 97.13% in OVX + E20 (P <0.05), 204.84% in OVX + E100 (P <0.05), and 936.45% in OVX + E500 group by 77.25% in OVX + P 2 (P <0.05) and 235.25% in OVX + P 10 group (P <0.05) .② Compared to ovariectomized rat, the nu mber of mast cells in uteri decreased by 32.65% in OVX + E 20,64.50% in OVX + E 100 (P <0.05), 74.49% in OVX + E 500 (P <0.05) .Wowever, the number of mast cells increased by 66.73% in OVX + P 2 group (P <0.05) compared with OVX.The trend of mast cells number in the rat uterus was decreased gradually with the increase of estrogen or progesterone concent ration. The number of mast cells in ovariectomized rat uterus was affected by estrogen or progesterone. These results of that estrogen or progesterone directly affected the number of mast cells in the uterus of rat.