Cytopathology is the study of cells to detect diseases. The usual procedure is to obtain a sample, to fix it on a glass slide, treat it with various dyes and inspect it under a microscope. Differential staining allows identification of the cells and their state of health. Samples for cytology can be obtained in more than one way. Fine Needle Aspiration (FNA) is a type of biopsy in which tumor samples are taken through thin needles. Scrape or brush cytology is another technique in which cells are scraped or brushed from the organ or tissue being tested. Samples from the esophagus, stomach, bronchi (breathing tubes that lead to the lungs), mouth, and cervix (Pap smear) can be obtained using this type of procedure.