Pores of Kohn

Development of Alveolar Septa and Formation of Alveolar Pores during the Early Postnatal Period in the Rat Lung

“…The present investigation on lung tissue of rats in the first three weeks after birth demonstrates that as secondary curved crests grow toward each other, alveolar openings arise from day 7 onward, bounded by the characteristic, ordered fine structure of alveolar pores, as first demon strated by Boatman and Martin [1963] and later confirmed by others [e.g.. Cordingley, 1972;Desplechain etal.. 1983]: (1) combined light-and electron-microscopic investiga tion demonstrates the occurrence of genuine pores: (2) the margin of the opening is covered by a continuous sheath of cytoplasm of pneumocytes whose tight junctions can be observed on one or both sides of the opening; the length of the major axes of the orifices of the openings is often between 1 and 15 gm: (3) elastic fibres at the apex of the interstitial layer of the septa appear near the basal lamina of the alveolar epithelial cells: (4) blood capillaries are invariably found in the apices of the septa, often in juxta position to the elastic fibres; (5) the presence of alveolar macrophages found in openings bounded by the paren chymal tissue of outgrowing septa is another indication that pores are involved, and (6) the present investigation confirms the view of Boatman and Martin [1963] that alve olar pores are formed during the development of the respi ratory tissue of the lung.…”

“…1974], This may partly explain the appearance of type II pneumocytes near the rim of pathological interalveolar apertures [Schaefer et al. 1964;Cordingley. 1972: Desplechain et al.…”

The mercurial nature of neutrophils: still an enigma in ARDS?

“…Migration of neutrophils out of the endothelium and across the pulmonary interstitium is thought to be mediated by fibroblasts, which establish defined conduits that assist neutrophils to gain access to the basal surface of the epithelium (177), while at the same time maintaining capillary-alveolar integrity (157). These conduits are likely to be anatomically different to the interalveolar connections, known as the pores of Kohn, which connect adjoining alveolar sacs (37). These interalveolar connections are the size of an alveolar epithelial cell and act to maintain gaseous exchange throughout the respiratory cycle.…”

Collateral Ventilation

“…The pores of Kohn allow the passage of air, alveolar lining fluid and cells between adjacent alveoli. Electron-microscopic studies confirmed the existence of the pores of Kohn by demonstrating intact epithelium-lined alveolar walls shaping the pores [13,14]. In most of these studies, examinations were performed in instillation-fixed, dried lungs showing widely opened pores.…”

“…He revealed fibrin strands entering the alveolar wall from one alveolus into the adjacent alveolus in a lung preparation of a patient who died of organizing pneumonia [13,14]. He did not use the term ‘pores of Kohn' himself, but his tutor Gustav Hauser [15] named these interalveolar pores as ‘pores of Kohn' in 1894.…”