When a bleb ruptures the air escapes into the chest cavity causing a pneumothorax (air between the lung and chest cavity) which can result in a collapsed lung. If blebs become larger or come together ...

that extend throughout the body cavity and into the wing and leg bones 2. Most birds have nine air sacs: two cervical, two cranial thoracic, two caudal thoracic, two abdominal, and a single ...