An extension of the parabronchus, the walls of which are the site of gas exchange. [ https://www.worldcat.org/search?q=bn%3A0073040584 http://www.vetmed.vt.edu/education/Curriculum/VM8054/Labs/Lab26/Examples/exairves.htm ]

Synonyms: air vesicle air capillary

This is just here as a test because I lose it