Trachea annular ligaments of trachea. The epiglottis closes the opening to the larynx during swallowing. The trachea develops in the second month of development. It is lined with an epithelium that has goblet cells which produce protective mucins (see "Respiratory epithelium"). An inflammatory condition, also involving the larynx and bronchi, called croup can result in a barking cough. A tracheotomy is often performed for ventilation in surgical operations where needed. Intubation is also carried out for the same reason by the inserting of a tube into the trachea. From 2008, operations have experimentally transplanted a windpipe grown by stem cells, and
Explorers of the Human Body weeks. It was later decided that instead of a hiatus, the program will end the season with thirteen episodes. Super Junior decided to leave the show due to their occupied schedules and busy preparations for their upcoming Asia-wide concert tour, Super Show. However, representatives of the program stated if there is a chance, a second season is considered. "Change", the variety program hosted by Lee Hyo-ri and Shin Dong-yup with Noh Hong-chul, Kangin, Son Ho-young and Min Kyung-hoon as regulars, took over the time slot. Explorers of the Human Body Explorers of the Human Body (Hangul: 인체탐험대; Hanja: 人體探險隊) was