Procedure of H-E Stain
First, the pathological sections were fixed with 95% ethanol (Tianjin Fuyu Fine Chemical Co., Ltd., China) for 15 minutes and washed with distilled water (Wenzhou Ou Hainan Dai E-commerce Co., Ltd., China) for 1 minute. Then the endometrial nucleus was stained by hematoxylin (Zhuhai Beso Biological Co., Ltd., China) for 3-5 minutes, and washed with distilled water for 1 minute. Next, they were immersed in 1% hydrochloric acid alcohol (Guangzhou Hewei Medical Technology Co., Ltd., China) for 3-5 seconds, and washed with distilled water for 1 minute. We immersed them in 1/500 ammonia water (Guangzhou Hewei Medical Technology Co., Ltd., China) for 10 seconds, and washed with distilled water for 1 minute. The endometrial cytoplasm were stained by eosin (Zhuhai Beso Biological Co., Ltd., China) for 1 minute, and washed with distilled water for 1 minute. The sections were dehydrated with 80%, 95%, and anhydrous ethanol (twice) for 10s every time, then with xylene (Tianjin Fuyu Fine Chemical Co., Ltd., China) (twice) for 1minute each time. Finally, the sections were closed with neutral gum (Shanghai Specimen and model Factory, China).