tonsillae

Tonsillae are a group of lymphoid tissues that form part of the immune ring known as Waldeyer's ring, lining the mucosa of the upper respiratory tract. They help defend against inhaled or ingested pathogens and are most prominent in childhood. The main components are the palatine tonsils (tonsillae palatinae), pharyngeal tonsil (tonsilla pharyngea, commonly called adenoids when enlarged), lingual tonsils (tonsillae linguales), and tubal tonsils (tonsillae tubales) near the openings of the auditory tubes.

Anatomy and distribution

- Palatine tonsils sit in the tonsillar fossae between the palatoglossal and palatopharyngeal arches.

- The pharyngeal tonsil is located on the roof of the nasopharynx.

- Lingual tonsils are at the posterior aspect of the tongue.

- Tubal tonsils lie around the pharyngotympanic tube openings.

Together, these structures form a ring of lymphoid tissue that surveils antigens entering through the nose and mouth.

Histology and function

Tonsillae consist of lymphoid tissue with follicles and germinal centers, supported by epithelium (palatine tonsils are covered by stratified squamous epithelium; others by respiratory epithelium). Crypts in the palatine tonsils increase surface area for antigen exposure. They contribute to humoral immunity by producing B cells and IgA antibodies and participate in mucosal immune responses.

Clinical significance

Tonsillae can undergo hypertrophy, particularly in children, sometimes causing snoring or airway obstruction. They are common sites of recurrent infections, including tonsillitis, and may be associated with peritonsillar abscess. Treatment options include tonsillectomy and, when indicated, adenoidectomy for adenoids. Age-related involution reduces their size in adulthood.