INTERACTIVE 3D MODEL

EPITHELIUM OF THE TRACHEA

 

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EPITHELIUM OF THE TRACHEA

 

Much of the upper airways are lined by pseudo-stratified ciliated columnar epithelium. Recall that pseudostratification means that despite the appearances in two dimensions, all of the cells connect with the basement membrane.  The functions of the upper airways are numerous but include gas transfer, humidification, immune surveillance and clearance of foreign material. The epithelial present helps perform many of these roles. Mucin secretion helps lubricate the airways and trap foreign material which is in turn cleared by a “wave-like” beating of the small hair like projections (cilia) on the surface of the cells. This function can be seen in the animation opposite. A range of inflammatory cells are present throughout the epithelium forming and integral part of immune surveillance.

 

Read more about surrounding structures or damage to the epithelium due to smoking cigarettes.

 

 

 

 

SURROUNDING STRUCTURES

 

The images left and below show how the epithelium us situated within the trachea as a whole and identifies structures surrounding the epithelium.

CLINICAL RELEVANCE: METAPLASTIC CHANGES IN TRACHEAL EPITHELIUM CAUSED BY SMOKING

 

Many of the constituents of cigarette smoke are irritating or toxic towards the glandular pseudostratified columnar epithelium of the airways. Squamous epithelium, which is thicker and tougher, is better suited to dealing with smoke related injury and therefore airways can undergo a change in cell type (metaplasia) from columnar to squamous. As a result, although squamous epithelium is not normally present in the airways, smoking can give rise to squamous cell carcinoma with the metaplastic change representing an early intermediary step towards malignancy.

 

The image on right shows two small fragments from the same biopsy. At the top of the screen it is easy to discern cilia on these columnar cells and this therefore represents genuine respiratory epithelium. At the bottom of the image the strip of epithelium is multilayered and stratified. This fragment represents squamous metaplasia of the airways.

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