Adenoids (Pharyngeal Tonsil)

Click to View Larger Image

The adenoids, also known as the pharyngeal tonsils, are a part of the lymphatic system located in the back of the throat and up into the nasal cavity. Much like the tonsils (palatine tonsils), the adenoids are made up of folded lymphatic tissue, lined with epithelial cells, house mucosal glands, and are covered in cilia and mucus. One single such fold is termed an adenoid. The hair-like cilia on the ciliated epithelial cells wave within the throat like seaweed along the shore, constantly sweeping materials out of the throat to catch possible infectious agents, coat them in mucus, and send the resulting mass to the stomach for digestion before the allergens, viruses, etc. can be drawn into the lungs to cause infection. Located above the tonsils and behind the soft palate and nose, the fairly oblong adenoids cannot be seen directly but are part of the nasopharynx, the area between the nose and the pharynx. Adenoid tissue is unencapsulated, lacks crypts (it has furrows), and includes efferent as well as afferent lymphatics. The adenoids will reach full size at some point during early childhood and then diminish again in size prior to adulthood. However, infection can at any time cause enlarged adenoids that may not reduce in size after the infection has passed. Such inflammation can result in obstruction of the respiratory system, troubled breathing, and may lead to ear infections when the adenoids swell enough to block drainage from the middle ear (the Eustachian tubes). Proper drainage of the sinuses may be restricted as well.