Pathologists continue to lead in the investigation, identification, and understanding of disease. They do so through a close and careful examination of organs, tissues, body fluids, or cells and by studying disease processes in laboratory experiments. There are a large number of specialties in the field of pathology. They include autopsy, breast pathology, cytopathology, including Fine Needle Aspiration biopsy (FNA), gastro-intestinal and liver pathology, hematopathology, molecular pathology and cytogenetics, neuropathology, obstetric and gynecologic pathology, pediatric pathology, renal pathology, urologic pathology, and general surgical pathology. In the broadest terms, Anatomic Pathology comprises surgical pathology, cytopathology, and autopsy pathology. Anatomic examinations generally involve both gross (i.e. visible to the eye) and microscopic visual examination of tissues. These procedures employ special staining techniques and immunohistochemistry, a process for locating proteins in tissue cells, in order to visualize specific proteins and other substances around the cells. Anatomic pathologists have been moving more and more toward the molecular level to gain additional clinical information on individual specimens. Although autopsy pathology accounts for less than ten percent of the work of pathologists, it is the most commonly understood function of the pathologist. Surgical pathology is a large area of practice for anatomic pathologists, involving examination of surgical specimens and biopsies from patients. In general, cytopathology describes the microscopic study of diseases through fluids or tissue smears on a cellular level.