Monocytes are largest leucocytes, size 12−20μm, life span variable, from a few to several days, nucleus bean shaped phagocytic. Also called scavanger cells as they remove dead cells and cell fragments, 3−8% of total.
Basophils are least numerous. They have 2−3 lobed twisted nucleus. Their granules are larger and fewer. These stain with basic dyes like methylene blue. These corpuscles, contain heparin, histamine and serotonin.
Erythrocytes occur only in vertebrates and are the most abundant of blood corpuscles. They are meant for transportation of respiratory gases mainly O2.
Lymph oocytes are small and roughly spherical corpuscles, comprising about 20% to 40% of the leucocytes. These are comparatively less motile, possess a large subspherical nucleus and produce antibodies.