Urinary bladder. Coloured urogram (X-ray) of a healthy human bladder (yellow, lower centre). The bones (yellow/magenta) of the pelvis (at left & right) and spine (upper centre) are also seen. The bladder here is partially only filled with urine. Urine is stored in the bladder between it being produced in the kidneys and excreted. A urogram is made by injecting a substance into the blood which is opaque to X-rays. An X-ray is taken after the kidneys have filtered this substance from the blood and it has collected in the bladder.