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
What Is Life Harrison performances" (just three of which date from the ex-Beatle's solo years) and described the track as an "exultant song of surrender", abetted by Harrison's "pumping fuzz guitar" and the song's "singalong magnetism". AllMusic's Richie Unterberger similarly praises "What Is Life" for its "anthemic" qualities, "particularly snazzy horn lines", and a guitar riff that is "one more entry in the catalog of George Harrison's book of arresting, low, descending guitar lines". Writing in the book "1,000 Recordings to Hear Before You Die", author Tom Moon refers to "the upbeat single 'What Is Life'" as an example of how Harrison "grabs