abnormal platelet physiology abnormal platelet dense granule physiology MP:0009446 MPheno.ontology abnormal delta granule physiology abnormal dense body physiology any functional anomaly of the specialized secretory organelles located in the small, irregularly shaped anuclear cells derived from fragmentation of precursor megakaryocytes that contain adenine nucleotides (ADP and ATP), ionized calcium, histamine, serotonin, and epinephrine