White blood cells, normally 5000-9000/mm3; includes polymorphonuclear neutrophils, lymphocytes, monocytes, polymorphonuclear eosinophils, and polymorphonuclear basophils. A ‘white cell count’ determines the total; a ‘differential cell count’ estimates the numbers of each type.
Fever, haemorrhage, and violent exercise cause an increase (leucocytosis); starvation and debilitating conditions a decrease (leucopenia).




