Procedure of Papanicolaou Stain
First, the pathological sections were fixed with 95% ethanol for 10 minutes and placed in 80%, 70% and 50% ethanol for 1 minute in sequence. The samples were placed in distilled water for 1 minute after ethanol every time. Then, the endometrial nucleus was stained by hematoxylin for 3-5 minutes, and washed with distilled water for 1 minute. We immersed the sections in 1% hydrochloric acid alcohol for 3-5 seconds, and washed with distilled water for 1 minute. Next, they were immersed in 1% saturated lithium carbonate solution (Guangdong Wengjiang Chemical Reagent Co. Ltd., China) for 2 minutes, and washed with distilled water for 1 minute. After that, they were immersed in 50%, 70%, 80% and 95% ethanol for 1 minute in sequence. Then we immersed them in orange G6 (Zhuhai Beso Biological Co., Ltd., China) for 2 minutes and washed with 95% ethanol twice, 10 seconds each time, then placed them in EA50 for 5-10 minutes. The sections were dehydrated with 95% ethanol (twice), anhydrous ethanol (twice) for 10s every time, then with xylene (twice) for 1minute each time. Finally, the sections were closed with neutral gum.