Institutional Closing

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Histology of Respiratory System

The Trachea

Identification:

The trachea slides can be identified at both lower power (first slide) or high power (second slide) by the distinctive purple-staining hyaline cartilage (1). At low power these form C-shaped rings (it appears as smaller segments in the first slide because it is an oblique section through the trachea and segments from several rings are seen).

Features to know:

  • Hyaline cartilage (1)
  • Pseudostratified ciliated columnar epithelium (2) lining the inside of the trachea
  • Gobet cells within the epithelium (5)
  • Trachealis muscle "closes" the C-shapred rings of cartilage, but is not very clear in the low power slide. Its approximate location is indicated by (3)

Other features:

The circular structures (4) are mucus glands.

Trachea Low
Trachea Hi

The Lung

Identification:

The lung slides can be identified by the thin layers of cells (simple squamous) arranged to form large, empty sacs (alveoli).

Features to know:

  • Alveoli are the individual sacs
  • Simple squamous epithelium surrounds each alveolus and consists of Type I and Type II cells
  • Type I cells (1) are squamous (flattened), have an oval nucleus and function in gas exchange
  • Type II cells (2) are cuboidal (squarish), have a round nucleus and produce surfactant
Lung Hi
Lung Type I and II
Lung Hi