Sentence:  The epithelial lining of the <WSD>vagina</WSD> consists of many layers of flattened cells. Changes in the condition of these cells during the menstrual cycle can be detected by swabbing the lining and looking at the cells under a microscope. 
Meaning of the word marked with <WSD> tags:  The passage leading from the opening of the vulva to the cervix of the uterus for copulation and childbirth in female mammals.