SUPPLEMENTARY:

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Trachea (LP)
longitudinal section

The trachea is lined by a respiratory epithelium which is a pseudo-stratified columnar epithelium with cilia and goblet cells. Cilia cannot be distinguished here at low power, but several pink staining goblet cells can be identified lying between the ciliated columnar cells at the top of the picture.

Immediately beneath the epithelium is the lamina propria. It contains abundant elastic tissue and a rich capillary bed which ensures that the air is warmed as it passes deeply into the respiratory system.

The submucosa contains many pink stained mucous glands lying in loose connective tissue and pink stained tracheal rings, cut in transverse section. The cartilages are surrounded by dense fibrous tissue, the perichondrium.