Objective: To examine possible estrogen dependent endometrial expression of MMP-26 in vitro. Design: Experimental study. Setting: Department of Obstetrics and Gynecology of the Palacky University Medical School and University Hospital, Olomouc, Czech Republic, Department of Obstetrics and Gynecology, University Hospital, Lund, Sweden. Methods: We studied MMP-26 mRNA in 14 normal endometrial samples obtained from the proliferative phase of the menstrual cycle. Samples were cultured for fi ve days either with estradiol alone or in combination with progesterone. Samples cultured with ethanol represented control groups. MMP-26 mRNA expression was examined in frozen samples using in situ hybridization. Immunohistochemistry was used to study the presence of estrogen and progesterone receptors in endometrial explants. Results: MMP-26 mRNA expression was highest in fresh (non cultured) samples. Signal intensity decreased during the fi rst two days of culture and was negligable in the following days. Nuclear intensity for estrogen and progesterone receptor was high after fi ve days of culture. Conclusion: We did not fi nd MMP-26 mRNA in vitro expression to be directly estrogen dependent.

        Key words: endometrium, in vitro, MMP, mRNA, regulation