What fluids are similar to CSF in their low celularity. They are composed mostly of small mononuclear cells and virtually no erythrocytes. They also have a low protein concentration.

Cytology is the exam of a single cell type, as often found in fluid specimens. It's mainly used to diagnose or screen for cancer. It's also used to screen for fetal abnormalities, for pap smears, to diagnose infectious organisms, and in other screening and diagnostic areas."