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.
Infundibulum - the infundibulum is the passage from the calyx to the renal pelvis. A single infundibulum may accept urine from several calyces. A kidney will usually have three to seven infundibulae. Lower pole - the bottom part of the collecting system. Stones in this location are generally the most difficult to treat. Stone fragments tend to persist in this location and act as seeds of recurrent stones. Medulla - inner solid portion of kidney where urine is formed and concentrated. Mid pole - middle portion of the collecting system usually composed of infundibulae which often drain a single calyx. Middle Ureter - the portion of the ureter which overlies the bony pelvis.