A polychrome staining method originally developed by George N. Papanicolaou. Routinely used in all cytology labs for staining cells so that they can be seen microscopically. Is excellent for evaluating nuclear and cytoplasmic structure. Is the microscopic examination of exfoliated cells obtained by swabs from the uterine cervix (cytology). Abnormal cells showing morphological signs of papillomavirus infection and/or malignant changes can be identified, in which case usually a direct inspection of the cervix (colposcopy) is performed, eventually followed by biopsy and histological diagnosis. Cytology is currently used as the method in cervical cancer screening programs. Because of the relatively high false-negative rate of cytology, it is being evaluated if detection of papillomavirus infection may become a supplementary method in cancer screening.