section_path: Microanatomy/Variation
section_name: Variation
paragraph_text: Variation
  
  The lobes of the lung are subject to anatomical variations. A horizontal interlobar fissure was found to be incomplete in 25% of right lungs, or even absent in 11% of all cases. An accessory fissure was also found in 14% and 22% of left and right lungs, respectively. An oblique fissure was found to be incomplete in 21% to 47% of left lungs. In some cases a fissure is absent, or extra, resulting in a right lung with only two lobes, or a left lung with three lobes.
  
  A variation in the airway branching structure has been found specifically in the central airwaybranching. This variation is associated with the development of COPD in adulthood.