Histology of Respiratory System | BCTC

Histology of Respiratory System

The Trachea


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-shaped 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


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