Image: lung of a rat. Gomori's trichrome staining.
Bronchi: they are the larger respiratory ducts. In this image, a part of a bronchus is shown with ciliated cuboidal epithelium and hyaline cartilage.
Cartilage: it is the tissue that maintains the bronchus shape. It is hyaline cartilage.
Respiratory bronchioli: they are the bronchioli connecting with the alveoli sacs.
Alveoli sacs: they are the spaces wit walls formed of alveoli.
Blood vessels: the lung is irrigated by a large amount of blood vessels, largely capillaries found in the alveoli. Ther large blood vessels enter the lung lobes at the same points as primary brochioli do.
Alveoli: they are small cavities lined by squamous epithelium and strongly irrigated by blood capillaries. Alveoli are the structures where the gas exchange happens. They are opened to the alveoli sacs.