Anwar Ul Haque
Department of Pathology, Pakistan Institute of Medical Sciences, Islamabad, Pakistan

Man is composed of tissues. Tissues are made up of cells. And the diseases occur in cells. Cytology is study of cells, a study of the cell at core. Light microscope is a powerful tool and can detect most morphological changes at cell level. Even the chemical changes, not visible can be detected through various immunological and hybridization techniques at cell level. Cytology is therefore a very useful technique and mode of study. The study of peripheral smear of
the blood in practice for so many decades is a form of cytology and of course bone marrow too.