Study of the cyclic changes of endometrial vasculatures with murine menstruation model

Objective: To study the cyclic changes of endometrial vasculature morphology and the volume fractions of endothelial cells with a murine menstruation model.Methods: Thirty-four adult ovariectomized C57BL/6 mice were used.After sequence hormone tseatment,0.2 ml arachis oil was injected into the uterine lumen to induce the decidual response,and the mice in control group were sham-operated without oil injection.Uteri of different groups were collected individually.Routine HE staining was carried on paraffin-embedded sections.The vasculature was displayed by immunohistochemistry with anti-CD31 monoclonal antibody.The computer image analysis software CAST2 was used to measure the volume fractions of endothelial cells.Results: HE staining displayed the endometrial sloughing at 30~35 hrs after oil treatment.At this time point,the endometrial vasculature showed two zones with immunohistochemistry.In the outer zone which was near the myometrium,vessels were evenly distributed while the vessels in the inner zone messed under the subluminal surface.In control group,endometrium remained intact and the whole layer of endometrial vasculature was disorganized.After oil treatment for 56~70 hrs,the epithelium was re-constructed in the experimental group,but the vessels were sparse and disorganized.In control group,the epithelium and vessels all appeared intact.Volume fraction of endothelial cell strikingly decreased only at 56~70 hrs after oil injection. Conclusions: The endometrial vasculature of this model showed two zones,which were morphologically similar to human endometrial functionalis and basalis.Volume fraction of endothelial cell only decreased after oil treatment for 56~70 hrs,whereas other groups did not show significant difference.