WORKSHOP IN HISTOLOGY, CYTOLOGY AND EMBRYOLOGY - 2016

Chapter 5. SPECIAL HISTOLOGY

Respiratory Organs

Slide 115. Lung.

Staining: hematoxylin and eosin.

Magnification: x80.

Most commonly, the section passes through an area of the lung containing Bronchi of various calibers and numerous alveoli, which appear as a delicate meshwork.

At low magnification, a large bronchus is identified (1). In its wall, we distinguish the respiratory mucosa (2). The submucosa contains numerous seromucous glands (3). At the border between the epithelium and the submucosa in the wall of the large bronchus lies the muscularis mucosae. The fibro-cartilaginous tunic (4) is represented by quite large plates of hyaline Cartilage.

A medium-sized bronchus (5) is lined with the same epithelium as the large one. The lamina propria and muscularis mucosae (7) are well developed. The submucosa contains mucous glands (8). The hyaline cartilages of the fibro-cartilaginous tunic appear as separate small plates (9). The Connective Tissue of the adventitia (10) transitions smoothly into the interalveolar connective tissue of the Lungs.

A small bronchus (11) is smaller in diameter than the medium one. Its epithelium is pseudostratified cuboidal. The lamina propria is thin. The muscular layer is well developed. Glands and cartilage are absent.

The slide also allows us to distinguish the transition of a small bronchus into bronchioles and alveolar ducts (12). The latter feature wall protrusions—pulmonary alveoli (13). The alveolar wall is formed by a single layer of type I and type II pneumocytes (alveolocytes). Externally, Blood capillaries and interalveolar septa (loose connective tissue) are adjacent to them.

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Slide 115. Lung.