Tonsil
Sagittal view of tonsils and throat anatomy
Details
SystemImmune system Lymphatic system
Identifiers
Latintonsilla, tonsillae (pl.)
TA98A05.2.01.011
FMA9609
Anatomical terminology

The tonsils are a set of lymphoid organs facing into the aerodigestive tract, which is known as Waldeyer's tonsillar ring and consists of the adenoid tonsil (or pharyngeal tonsil), two tubal tonsils, two palatine tonsils, and the lingual tonsils. These organs play an important role in the immune system.

When used unqualified, the term most commonly refers specifically to the palatine tonsils, which are two lymphoid organs situated at either side of the back of the human throat. The palatine tonsils and the adenoid tonsil are organs consisting of lymphoepithelial tissue located near the oropharynx and nasopharynx (parts of the throat).

Structure

Humans are born with four types of tonsils: the pharyngeal tonsil, two tubal tonsils, two palatine tonsils and the lingual tonsils.[1]

Type Epithelium Capsule Crypts Location
Pharyngeal tonsil (also termed "adenoid")Ciliated pseudostratified columnar (respiratory epithelium)Incompletely encapsulatedSmall folds—sometimes described as crypts[2]Roof of pharynx
Tubal tonsilsCiliated pseudostratified columnar (respiratory epithelium)Roof of pharynx
Palatine tonsilsNon-keratinized stratified squamousIncompletely encapsulatedLong, branched[3]Sides of oropharynx between palatoglossal
and palatopharyngeal arches
Lingual tonsilsNon-keratinized stratified squamousIncompletely encapsulatedLong, unbranched[3][4]Behind terminal sulcus (tongue)

Development

The palatine tonsils tend to reach their largest size in puberty, and they gradually undergo atrophy thereafter. However, they are largest relative to the diameter of the throat in young children. In adults, each palatine tonsil normally measures up to 2.5 cm in length, 2.0 cm in width and 1.2 cm in thickness.[5]

The adenoid grows until the age of 5, starts to shrink at the age of 7 and becomes small in adulthood.

Function

The tonsils are immunocompetent organs that serve as the immune system's first line of defense against ingested or inhaled foreign pathogens, and as such frequently engorge with blood to assist in immune responses to common illnesses such as the common cold. The tonsils have on their surface specialized antigen capture cells called microfold cells (M cells) that allow for the uptake of antigens produced by pathogens. These M cells then alert the B cells and T cells in the tonsil that a pathogen is present and an immune response is stimulated.[6] B cells are activated and proliferate in areas called germinal centers in the tonsil. These germinal centers are places where B memory cells are created and secretory antibody (IgA) is produced.

Clinical significance

Gross pathology of fresh hypertrophic tonsil. Top left: Surface facing the into the aerodigestive tract. Top right: Opposite surface (cauterized). Bottom: Cut sections.

The palatine tonsils can become enlarged (adenotonsillar hyperplasia) or inflamed (tonsillitis). The most common way to treat tonsillitis is with anti-inflammatory drugs such as ibuprofen, or if bacterial in origin, antibiotics, e.g. amoxicillin and azithromycin. Surgical removal (tonsillectomy) may be advised if the tonsils obstruct the airway or interfere with swallowing, or in patients with severe or recurrent tonsillitis.[7] However, different mechanisms of pathogenesis for these two subtypes of tonsillar hypertrophy have been described,[8] and may have different responses to identical therapeutic efforts. In older patients, asymmetric tonsils (also known as asymmetric tonsil hypertrophy) may be an indicator of virally infected tonsils, or tumors such as lymphoma or squamous cell carcinoma.

A tonsillolith (also known as a "tonsil stone") is material that accumulates on the palatine tonsil. This can reach the size of a peppercorn and is white or cream in color. The main substance is mostly calcium, but it has a strong unpleasant odor because of hydrogen sulfide and methyl mercaptan and other chemicals.[9]

Palatine tonsil enlargement can affect speech, making it hypernasal and giving it the sound of velopharyngeal incompetence (when space in the mouth is not fully separated from the nose's air space).[10] Tonsil size may have a more significant impact on upper airway obstruction for obese children than for those of average weight.[11]

As mucosal lymphatic tissue of the aerodigestive tract, the palatine tonsils are viewed in some classifications as belonging to both the gut-associated lymphoid tissue (GALT) and the mucosa-associated lymphoid tissue (MALT). Other viewpoints treat them (and the spleen and thymus) as large lymphatic organs contradistinguished from the smaller tissue loci of GALT and MALT.

Additional images

References

  1. ↑ "Definitive pharynx; Thyroid; Middle ear; Tonsils; Thymus". www.embryology.ch. Archived from the original on 22 November 2010. Retrieved 2018-10-15.
  2. ↑ Fagö-Olsen H, Dines LM, Sørensen CH, Jensen A (12 February 2019). "The Adenoids but Not the Palatine Tonsils Serve as a Reservoir for Bacteria Associated with Secretory Otitis Media in Small Children". mSystems. 4 (1). doi:10.1128/mSystems.00169-18. PMC 6372837. PMID 30801022.
  3. 1 2 "The Lymphatic System". act.downstate.edu. Archived from the original on 2017-02-02. Retrieved 2017-01-29.
  4. ↑ Shahid S. "Tonsils". Ken Hub. Retrieved 2023-01-17.
  5. ↑ Michaels L (1987). "Normal Anatomy, Histology; Inflammatory Diseases". Ear, Nose and Throat Histopathology. Springer London. pp. 265–272. doi:10.1007/978-1-4471-3332-2_26. ISBN 9781447133322.
  6. ↑ Kato A, Hulse KE, Tan BK, Schleimer RP (April 2013). "B-lymphocyte lineage cells and the respiratory system". The Journal of Allergy and Clinical Immunology. 131 (4): 933–57, quiz 958. doi:10.1016/j.jaci.2013.02.023. PMC 3628816. PMID 23540615.
  7. ↑ "Tonsils | Tonsilitis | Lymph Nodes". MedlinePlus. U.S. National Library of Medicine. Retrieved 2017-01-29.
  8. ↑ Ezzeddini R, Darabi M, Ghasemi B, Jabbari Moghaddam Y, Abdollahi S, Rashtchizadeh N, et al. (April 2012). "Circulating phospholipase-A2 activity in obstructive sleep apnea and recurrent tonsillitis". International Journal of Pediatric Otorhinolaryngology. 76 (4): 471–474. doi:10.1016/j.ijporl.2011.12.026. PMID 22297210.
  9. ↑ "Tonsil Stones Removal – What Are Tonsil Stones and How We Can Treat Them - eLimpid". elimpid.com. 2023-05-06. Retrieved 2023-05-11.
  10. ↑ Mora R, Jankowska B, Mora F, Crippa B, Dellepiane M, Salami A (September 2009). "Effects of tonsillectomy on speech and voice". Journal of Voice. 23 (5): 614–618. doi:10.1016/j.jvoice.2008.01.008. PMID 18468843.
  11. ↑ Wang JH, Chung YS, Cho YW, Kim DY, Yi JS, Bae JS, Shim MJ (April 2010). "Palatine tonsil size in obese, overweight, and normal-weight children with sleep-disordered breathing". Otolaryngology–Head and Neck Surgery. 142 (4): 516–519. doi:10.1016/j.otohns.2010.01.013. PMID 20304270. S2CID 42924590.
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