Basophils are one of the smallest populations of cells in bone marrow and blood (occurring <2% of all Leukocytes). Like neutrophils and eosinophils, they have lobed nuclei. They have only two lobes, and the chromatin filaments that connect them are not very visible. Basophils have receptors that can bind to IgE, IgG, complement, and histamine. The cytoplasm of basophils contains a varied amount of granules, these granules are usually numerous enough to partially conceal the nucleus. Granule contents of basophils are abundant with histamine, heparin, chondroitin sulfate, peroxidase, platelet-activating factor, and other substances.