Lower Respiratory System Laboratory

Gartner & Hiatt (atlas) 12:179-194

Slide #46 Larynx, human

( paraffin embedded, H&E stain). In this section of human larynx identify:

Ventricle. large fold invaginating from lumen with vocal cords on opposite sides of ventricle.
False vocal cords. respiratory (pseudostratified) epithelium containing ciliated columnar cells with underlying glands.
True vocal cords. non-keratinized, stratified squamous epithelium with underlying vocalis (sketetal) muscle without glands.
Glands. mucous and seromucous.
Lymphoid nodules (BALT, Bronchial Associated Lymphoid Tissue).
Cartilage

NOTE: The morphological integrity of these sections may have been disrupted during sectioning.

Slide #47 Trachea, human

(paraffin embedded, H&E stain). Cross-section of human trachea clearly exemplifying respiratory epithelium.

Identify:

Pseudostratified columnar epithelium. Find ciliated cells, goblet cells, basal cells, and perhaps brush cells with microvilli.
Basement membrane. Thick, beneath epithelium (light pink band with H&E).
Elastic fibers. Concentrate between lamina propria and glands in submucosa.
Glands. Mucous and seromucous.
Lymphocytes. Aggregates of small cells with nonsegmented nucleus
Blood vessels.
Hyaline cartilage. Individual slides may not contain complete cross-section of cartilage ring.
Fibrous perichondrium. Outer perichondrium merges with connective tissue.
Smooth muscle and connective tissue. Smooth muscle and connective tissue bridge open ends of cartilage.

NOTE: Some slides contain areas of hyperplasia in pseudostratffied epithelium and/or squamous metaplasia (smoker) -- look for squamous cells along luminal surface replacing pseudostratified organization.

Slide #84/98 Trachea, monkey

(paraffin embedded, H&E stain). Identify similar features in monkey trachea as found in human trachea (#47).

NOTE: Both slides also contain other structures.

Slide #48 Bronchus, human

(paraff in embedded, H&E stain). Cross-section of human lung containing bronchi. Identify and compare to tracheal components:

Respiratory epithelium & lining.
Bronchial lumen.
Hyaline cartilage. Incomplete rings or discontinuous plates.
Glands. mucous and seromucous .
Smooth muscle bundles.

NOTE: Some slides contain sections with no cartilage or submucosal glands characteristic of bronchi, but contain terminal bronchioles (see #52, dog lung). Also, several large blood vessels may be present.

Slide #50 & #49 Lung, human

(paraffin embedded, H&E stain). Peripheral portion of human lung.

Identify:

Bronchioles -- no cartilage/smooth muscle/ciliated/alveolar interface
Alveolar ducts and sacs
Blood vessels -- note integration within alveolar walls
Type I pneumocytes -- very thin cells lining alveoli/note juxaposition to vascular endothelium
Type II pneumocytes
Clara cells -- dome-shaped cells in bronchioles
Macrophages -- large cells in alveoli
Surfactant -- location

NOTE: Significant amount of debris (food) and neutrophils in alveolar spaces in many of these slides.

Slide #52 Lung, dog

(paraffin embedded, H&E satin). Most of these sections from dog lung contain a large pulmonary bronchus. NOTE: These sections are poorly stained.

Slide #150 Lung, rat

(paraffin embedded, Verhoff/van Gieson stain). These sections were stained with the Verhoff/van Gieson stain to emphasize the significant amount of elastic fibers present in lung: elastic fibers=black; collagen=rose; nuclei=black; cytoplasm=yellow. Identify fibers around individual alveoli and in bronchiolar muscularis and Clara cells in bronchioles. Remember that elasticity is critical to lung function.

A respiratory laboratory review is available.

Anne LeMaistre, M.D.