Ture about terminal bronchioles are all except ?

Terminal bronchioles contain Clara cells which secrete a protein that lines the small air passages. Alveoli (alveolar sac) are lined by type 1 pneumocytes (95%) and type 2 pneumocytes (5%). Type 2 pneumocytes secrete surfactant and also helps in repair of alveoli after destruction of type- 1 pneumocytes. Pores of Kohn are present in alveolar wall to allow passage of bacteria and exudate between adjacent alveoli.Terminal bronchi contain maximum smooth muscle cells relative to wall thickness.Cailage is found in larynx, trachea and bronchi but not in bronchioles.Submucosal glands are paicularly numerous in medium-sized bronchi and disapperar in distal terminal bronchioles.