[Quantitative analysis of the ultrasonogram and histological findings in normal airway wall].

There is a five-layer structure on the bronchial EBUS image including the first layer at the luminal side corresponding to the mucosa and inner part of the submucosa; the second layer corresponding to the outer part of submucosal tissue; the third layer corresponding to the inner perichondrium and the inner part of the cartilage; the fourth layer corresponding to the outer part of cartilage; the fifth layer corresponding to the outer perichondrium and the connective tissue outside the cartilage layer.