Importance of optimal mixtures of EDTA anticoagulant:blood for the preparation of well-stained avian blood smears.

1. This paper describes and illustrates the dangers of sub-optimal mixtures of EDTA anticoagulant:blood during the preparation of avian blood smears. 2. Excessive concentrations of EDTA lead to variable staining and make cellular differentiation more difficult. 3. It is recommended, for the use of a 2.5 ml graded blood tube containing 3.75 mg EDTA, that no less than 1.0 ml of blood be mixed.