Establisment And Identification Of Rat Thin Endometrium Model

OBJECTION:To explore a novel method to establish a thin endometrium by injecting ethyl alcohol into the uterine cavity of rat.METHOD:In order to establish thin endometrium model,25 sexual ly mature female virginal Sprague Dawley(SD)rats with normal estrous cycles were selected.They were divided into two groups:control group with 5 rats(10 uteri),and experimental group with 20 rats(40 uteri).Physiological saline was injected into uterine cavities from the corner and kept for 5 minutes during the laparotomy in the control group while 95% ethyl alcohol was injected in the experimental group and kept for 5 minutes and 10 minutes respectively. According to the time taken, the experimental group was divided into two subgroups:5 minutes group (10 rats with 20 uteri)and 10 minutes group(10 rats with 20 uteri).After two estrous cycles,we took uteri of rats in the estrogen period and measured the endometrial thickness:if the endometrial thickness in the experimental group was the same as that in the control group or the endometria were totally destroyed in the experimental group,that would mean the modelings fail;if the endometria were thinner in the experimental group than that in the control group,we would take these uteri as a new group-model group.Then we observed their endometrial morphology by hematoxylin-eosin staining(HE) and detected their cytokeratin,vimentin,VEGF and ERa expression using immuno-histochemistry method.Furthermore,we analysed the growth of the epithelial cells and cells in the stroma, VEGF and ERa expression to judge whether the models of thin endometria were successfully established.RESULTS:1. Two estrous cycles after ethyl alcohol was injected into the uterine cavities of rats, in 5 minutes group,one rat died and the endometrial thickness of four uteri was normal,while the endometria of fourteen uteri were thinner than that in control group. In 10 minutes group,two rats died and the endometrial layers even all uterus layers in 16 uteri were necrosed.2.Compared with control group,in model group,all layers of uterine were thinner, and this situation was more obvious in endometrial layer(234.6±48.1μm vs 764.1±100.2μm, p<0.01) than that in muscular layer. The endometrial lining was flat and smooth, without obvious wave. The glands were sparse and inactive or dilated and were represented by an inactive short columnar,cubic even flat epithelium of the endometrial type. Vessels were also sparse and dilated. In 10 minutes group, Most endometria were replaced by acellular structure area,only a few cellular structure outline left. Vessels in the musclar layer expanded and thrombosis inside were seen.3. Compared with control group, in model group,the cytokeratin area per unit endometrium area was less(11.46±2.40% vs 17.82±2.28%, p<0.05); the vimentin area per unit endometrium stromal area was also less(8.30±2.84% vs 13.62±3.18%, p<0.05); VEGF expressed lower in endometrium(0.033±0.0053 vs 0.054±0.0084, p<0.05);the expression of ERa in the endometrium was the same(3.12±0.07 vs 3.20±0.12, p>0.05).CONCLUSIONS:We successfully established a rat model of thin endometrium when 0.5ml 95% ethyl alcohol was kept in uterine cavities for 5 minutes, and the success rate was 70%.