human kidney in formalin solution closeup.

kidney organ human anatomy science isolated people body blood purification cleansing capillaries capillary urination urinary chemical regulation homeostasis urine production multipapillary system lumbar region retroperitoneally nephrons nephron renal arteries artery supply circulation abdominal aorta nerves nerve organic glass jar closeup formalin formaldehyde solution biology research medicine medical blue cloning cut out healthcare health life natural structure