En 1680-6433 2008-2177 Morphological and morphometrical changes of endometrim after application of estrogen and progesterone during luteal phase in the superovulated mice Background: The application of luteal phase supplementation hormones to increase the implantation rate is on debate among researchers. Objective: In this study, the morphological and morphometrical assessment of superovulated mice endometrium were investigated at window implantation period superovulated mice. Materials and Methods: Female mice were superovualated then were mated with vasectomized mice; the mice were divided in experimental and control groups. Experimental group included five groups which in them pseudopregnant mice were given a four consecutive daily injection of 1-progesterone (P), 2-estrogen (E), 3-estrogen + progesterone, 4-antiprogesterone+estrogen and 5-sham group. The uterine of all groups were collected after 4.5 day of pseudopregnancy and were prepared for histological and morphometrical studies. Results: Morphological studies of endometrial tissue showed that the luminal epithelium in group P appeared cuboidal shape. Endometrial folding was very high in group E+P. The luminal epithelium in groups E, E+P and RU 486 + E were seen in different morphology in comparison to control group. Morphometrical evaluation also showed height of luminal epithelium in group E (32.7±0.67) and E+P (33.6±1.3) were higher than those were seen in control (22.5±1.5) and group P (15.3±1.2). Conclusion: Progesterone caused the lowest endometrial development compare to other groups. It is concluded that the adding of E to P may improve endometrial condition to implant at luteal phase. Background: The application of luteal phase supplementation hormones to increase the implantation rate is on debate among researchers. Objective: In this study, the morphological and morphometrical assessment of superovulated mice endometrium were investigated at window implantation period superovulated mice. Materials and Methods: Female mice were superovualated then were mated with vasectomized mice; the mice were divided in experimental and control groups. Experimental group included five groups which in them pseudopregnant mice were given a four consecutive daily injection of 1-progesterone (P), 2-estrogen (E), 3-estrogen + progesterone, 4-antiprogesterone+estrogen and 5-sham group. The uterine of all groups were collected after 4.5 day of pseudopregnancy and were prepared for histological and morphometrical studies. Results: Morphological studies of endometrial tissue showed that the luminal epithelium in group P appeared cuboidal shape. Endometrial folding was very high in group E+P. The luminal epithelium in groups E, E+P and RU 486 + E were seen in different morphology in comparison to control group. Morphometrical evaluation also showed height of luminal epithelium in group E (32.7±0.67) and E+P (33.6±1.3) were higher than those were seen in control (22.5±1.5) and group P (15.3±1.2). Conclusion: Progesterone caused the lowest endometrial development compare to other groups. It is concluded that the adding of E to P may improve endometrial condition to implant at luteal phase. Mice, Morphometry, Estrogen, Progesterone, Luteal phase. Mice, Morphometry, Estrogen, Progesterone, Luteal phase. 133 142 oui jklji jkljioloo No