41. The ventral surface is stratified squamous non-keratinized epithelium which is smooth. 42. In 2007, an excitatory GABAergic system was described in the airway epithelium . 43. The respiratory tract is covered in epithelium , which varies down the tract. 44. The main bronchi have relatively large lumens that are lined by respiratory epithelium . 45. Usually there is hyperplastic and acanthotic epithelium with parakeratosis. 46. Club cells are found in the ciliated simple epithelium . 47. The epithelium contains many intimate and delicate connections to neural and connective tissue. 48. Unlike keratinized epithelium , nonkeratinized epithelium normally has no superficial layers showing keratinization. 49. Unlike keratinized epithelium, nonkeratinized epithelium normally has no superficial layers showing keratinization. 50. The outer layer is the epithelium , which is 25 to 40 lamellae.
