Clara cells are found in (AIIMS May 2013)
Bronchioles References: Pg. 1004; Gray's Anatomy (40th Ed.)
1. Clara cells are non-mucous and non-ciliated secretory cells found in the terminal/respiratory bronchioles of the lungs.
2. Clara cells are cuboidal and have short microvilli.
3. One of the main functions of Clara cells is to protect the bronchiolar epithelium.
4. They do this by secreting a small variety of products, including Clara cell secretory protein (CCSP) and a component of the lung surfactant.
5. They are also responsible for detoxifying harmful substances inhaled into the lungs.
6. Clara cells accomplish this with cytochrome P450 enzymes found in their smooth endoplasmic reticulum.
7. Clara cells also multiply and differentiate into ciliated cells to regenerate the bronchiolar epithelium.
8. The respiratory bronchioles represent the transition from the conducting portion to the respiratory portion of the respiratory system.
9. The narrow channels are usually less than 2 mm in diameter and they are lined by a simple cuboidal epithelium, consisting of ciliated cells and non-ciliated Clara cells, which are unique to bronchioles.
10. These play an important defensive role, and they also contribute to the degradation of the mucus produced by the upper airways.