RESUMO
The aim of this study was to investigate the morphological and ultrastructural changes of mouse endometrium by daily injection of progesterone, after ovarian hyperstimulation during preimplantation period. Material and NMRI mice, 6-10 weeks old, were initially hyperstimulated using hMG and hCG injection and then daily progesterone injection was performed subcutaneously [1 mg/mouse], thereafter they were mated artificially. 3.5 days after hyperstimulation, the animals were killed by cervical dislocation and the samples were obtained from 13 middle part of uterine horns. Specimens were also obtained from naturally and artifically impregnated control groups. The samples were devided and processed for light [H and E, PAS] and electron microscopic studies. Our results indicated that, daily injection of progesterone after hyperstimulation decreased the height of the epithelium. In the experimental group several fat droplets were seen in the basal part of epithelium. Also intercellular spaces were decreased decidualization was not seen. Results show that daily injection of progesterone after hyperstimulation altered the ultrastructure of endometrial epithelium which resulted in inhibition of decidualization reaction and can affect the uterine receptivity during implantation