Study of cells and their organizations including structure, functions and behaviour. Cytologic examinations may be performed on body fluids (examples are blood, urine, and cerebrospinal fluid) or on material that is aspirated (drawn out via suction into a syringe) from the body. Cytology also can involve examinations of preparations that are scraped or washed (irrigated with a sterile solution) from specific areas of the body. For example, a common example of diagnostic cytology is the evaluation of cervical smears (referred to as the Papanicolaou test or Pap smear).