Growth of the ferret tracheobronchial tree.

Because the ferret is being used increasingly in inhalation toxicology and lung physiology studies, it is necessary to better understand the airway structure of its tracheobronchial tree. Previously published information does not include dimensions of bronchi and bronchioles in either adult or growing ferrets. The airway structure of interest for calculating inhaled particle deposition patterns includes airway lengths, diameters and branching angles in each generation. Measurements of these dimensions were obtained for several selected airway paths on replica casts. Casts were made in-situ in four male litter mates age 14 hours, 9.5 days, 16.5 days and 56 days. These data demonstrate, that as with human lung growth, body length at a given age is a good predictor of airway lengths and diameters. Airway branch angles do not appear to change significantly during growth. Sufficient measurements were made to provide dimensions of a typical tracheobronchial pathway for this species. This pathway begins with the trachea and ends at the terminal bronchiole. The morphometric data were not sufficient to determine whether or not the number of tracheobronchial generations increase or decrease postnatally.