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 to Be Done? What Is to Be Done? What Is To Be Done? Burning Questions of Our Movement () is a political pamphlet written by the Russian revolutionary Vladimir Lenin (credited as N. Lenin) in 1901 and published in 1902. Lenin said that the article represented "a skeleton plan to be developed in greater detail in a pamphlet now in preparation for print". Its title is inspired by the novel of the same name by the 19th century Russian revolutionary Nikolai Chernyshevsky. In "What Is to Be Done?", Lenin argues that the working class will not spontaneously become political simply by fighting economic