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.
The renal corpuscle is the basic filtration structure of the kidney. Mammalian kidneys are a set of two, bean-shaped organs which normally lie on each side of the spine at the small of the back. Urine is produced in two well-defined regions of the kidneys, the renal cortex and the renal medulla.