source studies Blood 77 Cultured cells 22 Feces 11 Liver 10 Urine 9 Brain 8 Bacterial cells 7 Lung 7 Muscle 6 Macrophages 5 Tumor cells 4 Cecum 4 Heart 3 Intestine 3 Cyst fluid 2 Plant 2 Kidney 2 Cerebrospinal fluid 2 Amniotic fluid 2 Neutrophils 1 Ovarian cancer cells 1 Pancreas 1 Placenta 1 Plant roots 1 Saliva 1 Scalp 1 Skin 1 Soil 1 Spleen 1 Sputum 1