Basic and Clinical Sciences Examination (BCSE) Practice Exam 2025 – Comprehensive All-in-One Guide for Exam Success

Terminal bronchioles are the smallest airways in the conducting zone of the respiratory system, leading into the respiratory bronchioles and alveoli. The cells that are most characteristic of the histology of terminal bronchioles are Clara cells, also known as club cells. These cells play several important roles in the respiratory system. They are non-ciliated and have a distinctive dome shape. Clara cells are involved in the secretion of proteins such as surfactant proteins and various enzymes that help detoxify harmful substances inhaled into the lungs. They also participate in the repair process of the airway epithelium after injury.

While ciliated cells are present in the larger airways for mucociliary clearance, they are less prominent in terminal bronchioles. Type I pneumocytes are primarily found in the alveoli and are crucial for gas exchange but are not characteristic of terminal bronchioles. Endothelial cells line blood vessels and are not a feature of the airway epithelium. Hence, Clara cells are the defining cellular type within terminal bronchiole histology.