SUSUMU NISHINAGA / SCIENCE PHOTO LIBRARY SUSUMU NISHINAGA / SCIENCE PHOTO LIBRARY
Rat lung alveoli. Coloured scanning electron micrograph (SEM) of a section of a rat lung. Alveolar ducts (the larger passages) are surrounded by alveolar air sacs, which are clusters of alveoli. The alveoli provide the interface where gas transfer to and from the blood may occur. Several nearby alveoli may share the same connective tissue and blood capillaries. Magnification unknown.
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