A scanning electron microscopic study of alkali-digested human and rabbit alveoli.

Elastic fibers are fairly uniform in the size around all alveolar orifices and taper and branch continuously in the alveolar wall to form a spiderweb-like structure. Unusually large gaps of the elastic fiber network in the alveolar wall frequently show coiled ends or tissue debris at the margin. The latex-filled capillaries interweave and intersect with the elastic fibers and in many of these places appear to angulate or narrow acutely; these angulations may alter with lung inflation, affecting pulmonary vascular resistance. Disruption of fine elastic fibers in the alveolar wall could be related to the development of pulmonary emphysema.