Page 675 - Atlas of Histology with Functional Correlations

connective tissue below the epithelium are seromucous tracheal glands (8),

some of which open into the lumen of the bronchus (1). Also present in the
connective tissue is a lymphatic nodule (11) filled with lymphocytes. An
adventitia (10) surrounds the bronchus and its associated tissue. Outside the
adventitia of the intrapulmonary bronchus are thin-walled alveoli (4, 6).

FIGURE 17.13 ■ Intrapulmonary bronchus, cartilage plates, and surrounding
alveoli of the lung. Stain: hematoxylin and eosin. ×75.

From: Gartner LP, Hiatt JM. BRS Cell Biology & Histology. 6th ed. Baltimore: Lippincott
Williams & Wilkins, 2011.

FIGURE 17.14 | Terminal Bronchiole (Transverse

Section)

The bronchioles subdivide into smaller terminal bronchioles, whose diameters

are approximately 1 mm or less and their lumina lined with a simple columnar
epithelium (3). In the smallest bronchioles, the epithelium may be simple
cuboidal. The cartilage plates, bronchial glands, and goblet cells are absent from

the terminal bronchioles. The terminal bronchioles represent the smallest
conducting passageways for air.

Because of smooth muscle contractions, mucosal folds (7) are prominent in
the bronchioles. A well-developed smooth muscle (5) layer surrounds the thin
lamina propria (6), which, in turn, is surrounded by the adventitia (8).

Adjacent to the bronchiole is a branch of the pulmonary artery (2). The

terminal bronchiole is surrounded by the lung alveoli (1). Surrounding the

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