Isotopes when written out are common nouns, and should begin with the uncapitalized element name, followed by a hyphen (not an em dash or en dash) and then the mass number. Examples are carbon-14 and uranium-235.
The central region of the kidney contains the renal pelvis, which is located in the renal sinus, and is continuous with the ureter. The renal pelvis is a large cavity that collects the urine as it is produced. The periphery of the renal pelvis is interrupted by cuplike projections called calyces.
Each kidney has a prominent medial indentation called the hilus which serves as the entry point of blood vessels, nerves and ureter. At the hilus an inner layer of the renal capsule extends into an internal cavity of the kidney called the renal sinus. This cavity is filled with blood vessels, nerves, and the tributaries of the collecting system that eventually form the ureters.