Talaat and Xi  numerically investigated aerosol deposition in a single terminal alveolus with rhythmical oscillations and found significantly different particle dynamics in comparison to that in alveolated ducts or respiratory bronchioles
The terminal membranous bronchiole gives rise to 3 generations of respiratory bronchioles
(airways with alveoli forming a component of their walls).
Because rats lack respiratory bronchioles
, they have simple acini.
In contrast, terminal and respiratory bronchioles
arising from each pathway revealed varying degrees of wall thickening and remodeling.
(1) The CAP criteria require "discrete foci of fibrosis in the walls of respiratory bronchioles
associated with accumulations of asbestos bodies in histological sections.'' The former criterion may be difficult to assess in cases with diffuse fibrosis and could overlap with other diseases showing similar changes, for example, respiratory bronchiolitis-associated interstitial lung disease or exposure to various dusts other than asbestos.
In the original article of Myers et al, (1) the major pathologic finding was the presence of RB: clusters of slightly golden colored alveolar macrophages ("smoker's macrophages") in the lumens of respiratory bronchioles
, alveolar ducts, and in the surrounding alveoli.
Due to improved breathing pattern, respiratory bronchioles
may be widened, and perfusion of a large number of alveoli can be carried out efficiently.
The airway bifurcates repeatedly, and the airways from the 1st to the 4th generations are called bronchi, those from the 5th to the 16th generations are bronchioles, those from the 17th to the 19th are respiratory bronchioles
, and those from the 20th to the 23rd generations are alveolar ducts and sacs.
Intriguingly, these vessels reside in proximity to the respiratory bronchioles
, where the conducting zone, or anatomic dead space, transitions into the gas exchange region.
Although there are no recommendations regarding the utility of the percent predicted forced expiratory flow between 25% and 75% of vital capacity ([FEF.sub.25-75%]) by the American Thoracic Society (ATS) , some studies shows that silica dust exposure can cause widespread fibrotic lesions in small airways, affecting mostly the walls of membranous and respiratory bronchioles
and to a lesser degree alveolar ducts .
Low ERV in obesity suggests occurrence of tidal breathing close to RV in distal high resistance airways, such as noncartilaginous small membranous terminal and respiratory bronchioles
and alveolar duct, in obese populations (Figure 2).
The proposed pathogenesis of Swyer-James Macleod sydrome is bronchiolitis obliterans caused by respiratory infections in early childhood leading to inflammation, fibrosis and obstruction of the terminal and respiratory bronchioles
, possibly preventing normal development of the alveolar bud (Figure 4).