Bronchiole

Larger bronchioles, seen here, are lined by a ciliated, pseudostratified columnar epithelium that gradually changes to ciliated, simple cuboidal with decreasing numbers of goblet cells. A relatively thick layer of circular smooth muscle is present. Bronchioles lack both cartilage plates and glands. 200x

Larger bronchioles, seen here, are lined by a ciliated, pseudostratified columnar epithelium that gradually changes to ciliated, simple cuboidal with decreasing numbers of goblet cells. A relatively thick layer of circular smooth muscle is present. Bronchioles lack both cartilage plates and glands. 200x

Larger bronchioles, seen here, are lined by a ciliated, pseudostratified columnar epithelium that gradually changes to ciliated, simple cuboidal with decreasing numbers of goblet cells. A relatively thick layer of circular smooth muscle is present. Bronchioles lack both cartilage plates and glands. 200x

Larger bronchioles, seen here, are lined by a ciliated, pseudostratified columnar epithelium that gradually changes to ciliated, simple cuboidal with decreasing numbers of goblet cells. A relatively thick layer of circular smooth muscle is present. Bronchioles lack both cartilage plates and glands. 200x

Larger bronchioles, seen here, are lined by a ciliated, pseudostratified columnar epithelium that gradually changes to ciliated, simple cuboidal with decreasing numbers of goblet cells. A relatively thick layer of circular smooth muscle is present. Bronchioles lack both cartilage plates and glands. 200x

Smooth muscle forms the primary support for the bronchiole wall, where is forms the largest percentage of the wall thickness among respiratory passageways. Contraction of the smooth muscle regulates the diameter of the bronchiole; abnormal broncho-constriction, induced by allergens or inflammation, produces asthma.

This image was taken of a slide in the University of Tasmania slide collection.