Lungs are composed of a system of highly branched tubes that bring air into the alveoli, where gas exchange takes place. The proximal and distal regions of the lung contain epithelial cells specialized for different functions: basal, secretory and ciliated cells in the conducting airways and type II and type I cells lining the alveoli. Basal, secretory and type II cells can be grown in three-di...

The particle number concentration in ambient air is dominated by nanometer-sized particles. Recent epidemiological studies report an association between the presence of nanoparticles in inhaled air at the workplace and acute morbidity and even mortality in the elderly. A theoretical model of deposition of 20 nm particles in the human alveolus was formulated. Gas flow structure and deposition ra...

The histological changes of mammary glands ofguinea pigs during mid and late pregnancy, 1 day after parturition, peak lactation and 2, 3, 4, 8 and 12 days after weaning were studied. Rapid growth of the glandular tzssue occurred towards late pregnancy and was completed by peak lactation. Plasma cells occurred in large numbers in the interalveolar connective tzssue during the period between mid-...

A lveoli are the hallmark of lung structure. In 1959, when I embarked on studies of lung structure that ‘‘should interest physiologists’’, the first question I was asked was ‘‘how many alveoli are there in the human lung?’’ Along with Prof. D. Gomez, I counted alveoli by devising a now obsolete method [1], only to realise that what is of real functional importance is the design of the wall of t...

sacs,' which are main cavities of which the walls are constituted by alveoli or air-cells. By far the greater number of the lung alveoli belong to the air-sac system, but a very appreciable number belong to the atria, and the latter act partly as air-passages to the air-sacs, and partly perform the same respiratory functions as the air-sacs themselves. The walls of the atria have the same gener...

The architecture of the lung is discussed with special focus on lung parenchyma. The lung parenchyma is mainly comprised of numerous air-containing passages and intervening fine structures, corresponding to alveolar ductal lumens and alveoli, as well as alveolar septa and small pulmonary vessels occupying 10% of total parenchymal volume. The shapes and relative arrangements of alveolar ducts an...

TO THE EDITOR: Mysteries remain unresolved if the approach is misconceived. In this Viewpoint (3) alveoli are considered as structures sui generis—but they are not. Alveoli are rather air pockets within the ingenious architecture of a fiber continuum designed to expose capillary networks over a large surface to air refreshed from alveolar ducts (4). This fiber continuum spans from the periphera...

TO THE EDITOR: Mysteries remain unresolved if the approach is misconceived. In this Viewpoint (3) alveoli are considered as structures sui generis—but they are not. Alveoli are rather air pockets within the ingenious architecture of a fiber continuum designed to expose capillary networks over a large surface to air refreshed from alveolar ducts (4). This fiber continuum spans from the periphera...