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. Author manuscript; available in PMC: 2014 Mar 1.
Published in final edited form as: Biochim Biophys Acta. 2012 Sep 29;1831(3):612–625. doi: 10.1016/j.bbalip.2012.09.010

Fig. 4. Cartoon illustrating surfactant secretion, recycling, and catabolism.

Fig. 4

Surfactant is synthesized and secreted from distal lung alveolar type II epithelial cells using cellular substrates or from circulation. The newly synthesized surfactant phospholipids are packaged into a storage form, termed lamellar bodies. The secreted surface-active lipid material rapidly transforms into tubular myelin (not shown) that serves as a precursor to the monolayer film at the air-surface interface. During respiration, small and physiologically active large aggregates are formed that can be internalized and catabolized by alveolar cells, including macrophages. A significant portion of surfactant lipid is re-utilized by type II cells. Adapted and modified from M. Ikegami/Respirology 11 (2006), S24–S27.