Histology; normal and morbid.
- Dunham, Edward K. (Edward Kellogg), 1860-1922
- Date:
- 1898
Licence: Public Domain Mark
Credit: Histology; normal and morbid. Source: Wellcome Collection.
Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.
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![2. Pavement-epithelium.—This variety of epithelium consists of thin cells arranged edge to edge to form a single layer. With the exception of certain regions on the surfaces of the pulmonary alveoli, the ceHs are more cytoj)lasmic and granular than are those of endothelium which this tissue in other respects closely resembles. During fietal life the smaller air-])assages and alveoli of the lung are lined by a pavement-epithelium, the cells of which are nearly as thick as those of some varieties of cubical epithelium. When, lu»\v('ver, the lung is expanded by the respiratory acts following birth, many of the cells lining the alveoli become greatly extended and flattened until their boflies are thin and membranous and their nuclei inconsj)icuous or even destroyed (Fig. 30). These greatly flattened epithelial cells are found covering those portions of the Fig. 30. ravement-epithelium. Surface view ot the lining of a pulmonary alveolus ; man. (KoUiker.) (I, membranous cell without a nucleus; 6, nucleated granular cell; r, cut surface of the vertical wall of the alveolus, the structure of which is not represented. alveolar walls in which the capillary bloodvessels are situated and permit a ready interchange of gases between the air in the alveolar cavities and the blood circulating in their walls. Many of the epithelial cells covering the tissues in the meshes between the capillaries retain the cytoplasmic and granular character posses.sed before birth and appear capable of multiplying and, perhaps, replacing such of the thinner cells as may be thrown otf t)r destroyed. It will be evident, from the foregoing descriptions, that there](https://iiif.wellcomecollection.org/image/b21223841_0047.jp2/full/800%2C/0/default.jpg)
