source studies Blood 15 Bacterial cells 7 Cultured cells 6 Feces 6 Liver 4 Cells 4 Intestine 3 Muscle 3 Urine 3 Plant 2 Yeast cells 2 Brain 2 Leaves 1 Bee heads 1 Keratinocytes 1 Kidney 1 Amniotic fluid 1 Lung 1 Milk 1 Pancreas 1 Sputum 1 Tissue 1 Whole Tissue 1