Received February 14, 2022
Accepted September 26, 2022

Background: Mast cell population and histamine affect implantation of blastocysts. This study was aimed to evaluate the effect of progesterone administration after induction of ovulation on uterine tissue mast cell population and histamine content in mice. Methods: An experimental study was performed on three groups of mice; control group, induction of ovulation (induction group), and induction of ovulation along with progesterone administration (progesterone group). Mast cells were counted using toluidine blue staining and histamine level was measured through spectrophotometry. Results: According to the analysis of variance (ANOVA), there was no difference in mast cell population neither in endometrium (P =0.138) nor in myometrium (P =0.611). Nonparametric analysis showed different medians among the groups of endometrial samples in which the content of histamine in the progesterone group were lower than the median (P =0.020). This difference was not observed in myometrium (P =0.765). The ratio of mast cells in myometrium per endometrium increased in progesterone group in comparison to the control group based on a generalized linear model (P =0.041). Uterine histamine level was different between the groups based on ANOVA (P =0.039) in which progesterone group showed lower amounts of histamine. Conclusion: Progesterone administration after induction of ovulation may could not decrease the number of endometrial mast cells and might increase the ratio of myometrium mast cells per endometrium mast cell. Histamine level of uterus was decreased by administration of progesterone in ovulation induced mice.