The renal pelvis a) is formed by the expanded superior end of the ureter where it divides into the..

The renal pelvis

a) is formed by the expanded superior end of the ureter
where it divides into the medullary pyramids; not visualized sonographically
when collapsed.

 b) is another term for the renal hilum.

 c) is formed by the expanded superior end of the ureter
where it divides into the infundibula; not visualized sonographically when
collapsed.

d) can be visualized sonographically at the corticomedullary
junction when urine-filled.