BIO 241 HISTOLOGY REVIEW Respiratory System Dr. Tim Ballard Department of Biology and Marine Biology

Trachea Trachea –section – H&E – 4x objective C-shaped ring of hyaline cartilage submucosa lumen esophagus ciliated pseudostratified columnar epithelium The arrowhead indicates the trachealis muscle, which bridges the open ends of the C-shaped cartilage ring.

ciliated pseudostratified columnar epithelium Trachea Trachea –section – H&E – 10x objective ciliated pseudostratified columnar epithelium adventitia submucosa lumen hyaline cartilage adipose tissue

Trachea Trachea –section – H&E – 40x objective cilia ciliated pseudostratified columnar epithelium submucosa hyaline cartilage Although not shown in this view, goblet cells should be seen easily scattered throughout the epithelial layer.

Intrapulmonary bronchus Intrapulmonary bronchus – cross section – H&E – 10x objective ciliated pseudostratified columnar epithelium lumen alveoli The arrow shows a plate of cartilage, not a C-shaped ring. This is a diagnostic feature of this type of bronchus. Very little smooth muscle is present.

Bronchiole Bronchiole – cross section – H&E – 4x objective The arrow shows a bronchiole. Note that there are no plates of cartilage around it. The arrowhead points out a branch of the pulmonary artery.

Bronchiole Bronchiole – cross section – H&E – 10x objective smooth muscle The star shows a bronchiole. Note that there are no plates of cartilage around it.

ciliated simple columnar epithelium Bronchiole Bronchiole – cross section – H&E – 40x objective ciliated simple columnar epithelium Note the change in the epithelium to a short columnar/cuboidal with no goblet cells. Cilia are still present.

Respiratory bronchiole Respiratory bronchiole – cross section – H&E – 10x objective respiratory bronchiole Arrows indicate alveoli arises directly from the respiratory bronchiole. There is simple squamous epithelium and some smooth muscle. PA=pulmonary artery

Alveoli Respiratory bronchiole – cross section – H&E – 10x objective alveolar wall alveolar sac