Tonsil

Tonsil
sagittal view of tonsils and throat anatomy.
Details
Identifiers
Latin Tonsilla, Tonsillae (pl.)
MeSH D014066
TA A05.2.01.011
FMA 9609
Anatomical terminology

Tonsils are collections of lymphoid tissue[1] facing into the aerodigestive tract. The set of lymphatic tissue known as Waldeyer's tonsillar ring includes the adenoid tonsil, two tubal tonsils, two palatine tonsils, and the lingual tonsil.

When used unqualified, the term most commonly refers specifically to the palatine tonsils, which are masses of lymphatic material situated at either side of the back of the human throat. The palatine tonsils and the nasopharyngeal tonsil are lymphoepithelial tissues located near the oropharynx and nasopharynx (parts of the throat).

Structure

Tonsils in humans include, from anterior (front), superior (top), posterior (back), and inferior (bottom):

Type Epithelium capsule Crypts Location
Adenoids (also termed "pharyngeal tonsils")Ciliated pseudostratified columnar (respiratory epithelium)Incompletely encapsulatedNo crypts, but small foldsRoof of pharynx
Tubal tonsilsCiliated pseudostratified columnar (respiratory epithelium)Roof of pharynx
Palatine tonsilsNon-keratinized stratified squamousIncompletely encapsulatedLong, branched[2]Sides of oropharynx between palatoglossal
and palatopharyngeal arches
Lingual tonsilsNon-keratinized stratified squamousIncompletely encapsulatedLong, branched[2]Behind terminal sulcus (tongue)

Normally, each tonsil measures up to 2.5 cm in length, 2.0 cm in width and 1.2 cm in thickness.[3]

Development

Tonsils tend to reach their largest size near puberty, and they gradually undergo atrophy thereafter. However, they are largest relative to the diameter of the throat in young children.

We actually have four tonsils,the pharyngeal tonsil, tubal tonsil, palatine tonsil, lingual tonsil. The reason why a lot of people do not know this is because you can usually only see the two in the back, palatine tonsil, and lingual tonsil. [4]

Function

These immunocompetent tissues are 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. Tonsils have on their surface specialized antigen capture cells called M cells that allow for the uptake of antigens produced by pathogens. These M cells then alert the underlying B cells and T cells in the tonsil that a pathogen is present and an immune response is stimulated.[5] B cells are activated and proliferate in areas called germinal centres in the tonsil. These germinal centres are places where B memory cells are created and secretory antibody (IgA) is produced.

Recent studies have provided evidence that the tonsils produce T lymphocytes, also known as T-cells, in a manner similar to the way the thymus does.[6]

The many but small side effects of having tonsils are bleeding of the tonsils, chronic tonsillitis, and other rare diseases to your tonsils. Many of these symptoms are the common ailment to why many doctors recommend a tonsillectomy on their patients.[7]

Clinical significance

A pair of tonsils after surgical removal.

Tonsils can become enlarged (adenotonsillar hyperplasia) or inflamed (tonsillitis) and may require surgical removal (tonsillectomy). This may be indicated if they obstruct the airway or interfere with swallowing, or in patients with frequent recurrent tonsillitis. 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.

Tonsillitis is a disorder in which the tonsils are inflamed (sore and swollen). The most common way to treat it is with anti-inflammatory drugs such as ibuprofen, or if bacterial in origin, antibiotics, e.g. amoxicillin and azithromycin. Often severe and/or recurrent tonsillitis is treated by tonsillectomy.[9][10]

A tonsillolith is material that accumulates on the tonsil. They can range up to the size of a peppercorn and are white/cream in color. The main substance is mostly calcium, but they have a strong unpleasant odor because of hydrogen sulfide and methyl mercaptan and other chemicals.

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).[11] Tonsil size may have a more significant impact on upper airway obstruction for obese children than for those of average weight.[12]

As mucosal lymphatic tissue of the aerodigestive tract, the 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. ↑ "the definition of tonsil". Dictionary.com. Retrieved 2017-01-29.
  2. 1 2 "The Lymphatic System". act.downstate.edu. Retrieved 2017-01-29.
  3. ↑ Chapter: Ear, Nose and Throat Histopathology in L. Michaels (1987). Normal Anatomy, Histology; Inflammatory Diseases. Springer London. ISBN 9781447133322.
  4. ↑ "Definitive pharynx; Thyroid; Miiddle ear; Tonsills; Thymus". www.embryology.ch. Retrieved 2018-10-15.
  5. ↑ Kato A et al, B-lymphocyte lineage cells and the respiratory system, Journal of Allergy and Clinical Immunology, Volume 131, pages 933-957, 2013
  6. ↑ "Tonsils Make T-Cells, Too, Ohio State Study Shows". Ohio State University. Ohio State University, Comprehensive Cancer Center. March 4, 2012. Retrieved March 27, 2014.
  7. ↑ "Tonsillectomy - Mayo Clinic". www.mayoclinic.org. Retrieved 2018-10-11.
  8. ↑ Ezzeddini, R; Darabi, M; Ghasemi, B; et al. (2012). "Circulating phospholipase-A2 activity in obstructive sleep apnea". International Journal of Pediatric Otorhinolaryngology. 76 (4): 471–4. doi:10.1016/j.ijporl.2011.12.026. PMID 22297210.
  9. ↑ Udayan K Shah, MD, Associate Professor of Otolaryngology–Head and Neck Surgery, Jefferson Medical College, Thomas Jefferson University; Director, Fellow and Resident Education in Pediatric Otolaryngology, Attending Surgeon, Division of Otolaryngology, Nemours-AI duPont Hospital for Children
  10. ↑ "Tonsils | Tonsilitis | Lymph Nodes | MedlinePlus". Retrieved 2017-01-29.
  11. ↑ Mora, R; Jankowska, B; Mora, F; Crippa, B; Dellepiane, M; Salami, A (2009). "Effects of tonsillectomy on speech and voice". J Voice. 23 (5): 614–8. doi:10.1016/j.jvoice.2008.01.008. PMID 18468843.
  12. ↑ 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): 516–9. doi:10.1016/j.otohns.2010.01.013. PMID 20304270.
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