lung

Описание: Visceral pleura (serosa) surrounds the lungs. It consists of a thin layer of pleural connective tissue and a simple squamous layer of pleural mesothelium. Intrapulmonary bronchi branch into smaller bronchi and bronchioles. Bronchi contains hyaline cartilage plates and seromucous glands in their walls and their lumen is lined with pseudostratified ciliated columnar epithelium. The same epithelium lines the lumen of bronchioles. As a bronchiolus is getting smaller so does the epithelium change into simple ciliated columnar or simple cuboidal epithelium. Beneath the epithelium is the lamina propria. The lumen shows mucosal folds caused by the contractions of the surrounding smooth muscle layer. The bronchiole are surrounded by the adventitia. Connective tissue trabeculae and alveoli contain dust cells. Dust cells are blood monocytes that have entered the lung. Their primary function is to clean the alveoli of microorganisms and inhaled microparlicules by phagocytosis. The most of alveoli surface is lined with type I pneumocytes. These cells are very thin simple squamous alveolar cells. The alveoli is also lined with type II pneumocytes, which produce surfactant. The surfactant forms thin layer over the surfaces of type I pneumocytes and lowering the alveolar surface tension at the air-epithelium inrface. Interalveolar septa consist of a simple squamous alveolar cells, fine connective tissue fibres and fibroblasts and numerous capillaries. The oxygen from inhaled air has to go though wall of type I pneumocyte, wall of endothelial cell, which is lined the capillary, and their fused basal laminae. These layers are also called an air-blood barrier.

Stained: modified green trichrome (collagen tissue is green, muscle tissue is red, elastic fibres and nuclei of cells are black)
Author: Mgr. Tereza Blassová, Ph.D.
Scaning of the specimen: Mgr. Yaroslav Kolinko, Ph.D.