The chainsaw is a highly effective and efficient tree and branch cutting power tool. It works with an engine, referred to as a power head; powering a metal chain, driven by a centrifugal clutch, with a chain moving around a groove in the guide bar at fast speeds.
adenoids. 1  one of two masses of lymphatic tissue situated on the posterior wall of the nasopharynx behind the posterior nares. During childhood these masses often swell and block the passage of air from the nasal cavity into the pharynx, preventing the child from breathing through the nose.
The adenoid, unlike the palatine tonsils, has pseudostratified epithelium. The adenoid is often removed along with the palatine tonsils. Development. Adenoids develop from a subepithelial infiltration of lymphocytes after the 16th week of embryonic life. They are part of the so-called Waldeyer ring of lymphoid tissue which includes the palatine tonsils and the lingual tonsils.