File:Respiratory histology 03.jpg

From Embryology

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Respiratory Alveoli

Alveous cartoon

(Stain - Haematoxylin Eosin)

Structure of the functional unit of the lung, note the capillary embedded in wall. Compare the structure with alveoli cartoon.

Alveolar type I cells

  • small alveolar cells or type I pneumocytes
  • are extremely flattened (the cell may be as thin as 0.05 µm) and branched
  • form the bulk (95%) of the surface of the alveolar walls.
  • The shape of the cells is very complex, and they may actually form part of the epithelium on both faces of the alveolar wall.
  • multiple cytoplasmic plates and relatively devoid of organelles
    • plates represent the gas exchange surface in the alveolus.

Alveolar type II cells

  • large alveolar cells or type II pneumocytes
  • about as many type II cells as type I cells (cell shape accounts for small contribution to alveolar area).
  • irregularly (sometimes cuboidal) shaped.
  • form small bulges on the alveolar walls.
  • contain are large number of granules called cytosomes (or multilamellar bodies)
    • consist of precursors to pulmonary surfactant (mixture of phospholipids that keep surface tension in the alveoli low).
  • can act as a progenitor cell for both type I and type II cells.

Alveolar Macrophage

  • dust cell
  • monocyte-derived immune system cell
  • removes debris and microorganisms from the alveoli.
    • subset of pulmonary macrophages.

Respiratory Histology: Bronchiole | Alveolar Duct | Alveoli | EM Alveoli septum | Alveoli Elastin | Trachea 1 | Trachea 2 | labeled lung | unlabeled lung | Respiratory Bronchiole | Lung Reticular Fibres | Nasal Inferior Concha | Nasal Respiratory Epithelium | Olfactory Region overview | Olfactory Region Epithelium | Histology Stains

Links: Histology | Histology Stains | Blue Histology images copyright Lutz Slomianka 1998-2009. The literary and artistic works on the original Blue Histology website may be reproduced, adapted, published and distributed for non-commercial purposes. See also the page Histology Stains.

Cite this page: Hill, M.A. (2024, June 24) Embryology Respiratory histology 03.jpg. Retrieved from

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G

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15:47, 2 March 2011Thumbnail for version as of 15:47, 2 March 2011300 × 400 (27 KB)S8600021 (talk | contribs)==Respiratory Alveoli== Respiratory histology 03.jpg Original file name: Lun40he.jpg {{Template:Blue Histology}} Category:Respiratory