一些部位象子宫颈上皮很容易发生恶变，肿瘤筛选常常选宫颈上皮细胞进行实验室检查。图示是巴氏涂片后非典型增生的宫颈细胞的表现，细胞体积增大，胞核浓染，核体积缩小，细胞浆增多。
Some epithelia are accessible enough, such as the cervix, that cancer screening can be done by sampling some of the cells and sending them to the laboratory. Here is a cervical Pap smear in which dysplastic cells are present that have much larger and darker nuclei than the normal squamous cells with small nuclei and large amounts of cytoplasm.