Basic and Clinical Sciences (BCSE) Practice Exam

The key histological feature of bronchi is the presence of ciliated pseudostratified columnar epithelium. This type of epithelium is characterized by its column-like cells that appear to be multilayered due to the varying heights of the nuclei, but all cells are actually anchored to the basement membrane, making it a single layer. The ciliated aspect of this epithelium plays a crucial role in the respiratory system; the cilia help to trap and move particles and mucus out of the airways, thereby contributing to the defense mechanism of the lungs.

In relation to the other options, simple squamous epithelium, which is primarily found in areas requiring diffusion such as alveoli or capillaries, would not provide the necessary protection or functionality needed in the bronchi. Stratified columnar epithelium tends to be found in parts of the male reproductive tract and in larger ducts of some glands, rather than in the bronchi. Lastly, simple cuboidal epithelium is typical in smaller ducts and glands and doesn't match the structure observed in bronchi. Thus, the correct choice is the ciliated pseudostratified columnar epithelium, which is not only histologically