The tonsils are lymphoglandular organs located at the level of the mouth and pharynx. The term lymph gland refers to an organ having an anti-infective and immune function;
the task of the tonsils, in particular, is to protect the organism from pathogens that can invade the tissues around the orifices of the nasal and oral cavities. Other common lymph glands, present in the human body, are the lymph nodes.
The tonsils are distributed in different areas, between the oral cavity and the pharynx, therefore, they are identified by different names based on their position; in particular we have:
- the palatine tonsils, two in number (in common parlance, when we speak generically of tonsils we mean the palatine tonsils);
- the pharyngeal (rhino) tonsil (in common parlance, it is often called adenoid, and when it appears inflamed, then enlarged, we speak of adenoids);
- the lingual tonsil.
Anatomy of the tonsils
The tonsils are conspicuous agglomerations of lymphoid tissue, so much so that they can be considered real organs. At the pharyngeal level, for greater completeness of information, areas with such thickening alternate with less dense areas of lymphoid tissue (at this level we speak specifically of adenoid tissue).
Lymphoid tissue (also known as lymphatic or lymphoreticular tissue) is largely composed of cells called lymphocytes, supported by a dense connective network. Specifically, a connective scaffold with capillaries, arterioles and venules is recognized at the tonsillar level. In it take place the lymphoid (or lymphatic) follicles, which are aggregates of lymphocytes, ie cells with an anti-infective and immune function.
The palatine tonsil forms an ovoid mass.Shape and size are reminiscent of an almond and this explains why it is also known as amygdala, a term of Greek origin that indicates the almond. In the human body there are two palatine tonsils, which lodge symmetrically in a region called the isthmus of the jaws. This area connects the mouth and pharynx; it is formed by arched structures and, on the sides of them, there are precisely the palatine tonsils.
Given their position, the palatine are the only visible tonsils. The precise size of a single palatine tonsil can vary from individual to individual; the average data show these measures:
- height: 20-25 mm.
- length: about 15 mm.
- thickness: about 10 mm.
The surface of the palatine tonsil is lined with the pharyngeal mucosa. The mucosa is the portion of tissue in direct contact with the lumen of the animal hollow organs. The epithelium that covers the pharyngeal mucosa is classified as stratified pavement, that is formed by overlapping flattened cells. Through histological analyzes of the tonsillar epithelium, cavities, called crypts, also very deep can be noted. These structures allow to widen the contact surface with what penetrates the oral cavity from the outside, allowing a more efficient action against germs and bacteria. In fact, the mucous secretion containing the cells of the immune system collects inside the crypts.
The pharyngeal tonsil is located at the level of the nasopharynx, that is, the upper part of the pharynx, between the pharyngeal vault and the upper face of the palate. It is also called amygdala (pharyngeal in this case) by virtue of its shape, similar to that of an almond; more commonly it is known as adenoid. Like the palatine tonsil, its histological structure provides for the presence of crypts. it is a particular organ: after birth it develops progressively up to the 7-8th year, at which time it begins to atrophy naturally until it almost disappears, in some cases, in adulthood.
The lingual tonsil is located behind and at the base of the tongue. This area is covered by follicular agglomerates, that is, by lymphoid tissue, between which circular furrows insinuate. These grooves contain the tonsillar crypts, about 2-3 mm deep. Like the pharyngeal tonsil, the lingual tonsil also undergoes a process of involution starting from the age of about 14. Around the age of 20, the reduction of the lingual tonsil is complete, so much so that only a few small follicles remain.
Functions of the tonsils
The tonsils, together with other local lymphoid clusters (small islands of lymphatic tissue that connect them), make up the Waldeyer's lymphatic ring.
Due to their position, located at the beginning of the respiratory and digestive tracts, and their lymphoid composition, the tonsils play a very specific role: they are the first defense barriers against germs and bacteria that penetrate from the outside, through the "air and food substances." The anti-infective and immune action is favored by the presence of crypts. There are two reasons for this:
- The invaginations, or cavities, increase the contact surface between the tonsillar epithelium and external pathogens. In this way, the anti-infective action is more efficient.
- The epithelium of the crypts produces a lymphocytic infiltration inside the crypts. This guarantees an immune reaction of the antigen-antibody type.
The tonsils are particularly active in children until puberty.
Diseases of the tonsils
The pathologies are indicated with the generic term of tonsillitis. They affect the lymphoid tissue of the tonsils, giving rise to an "inflammation.
More precisely we are talking about:
- Tonsillitis, when inflammation affects the palatine and lingual tonsils.
- Adenoiditis, when inflammation affects the pharyngeal tonsil.
Furthermore, tonsillitis can be divided into:
- Acute palatine tonsillitis:
- Acute catarrhal tonsillitis
- Streptococcal tonsillitis
- Parenchymatous tonsillitis
- Peritonsillar abscess
- Acute lingual tonsillitis:
- Acute catarrhal lingual tonsillitis
- Suppurative lingual tonsillitis
For adenoiditis, we speak only of acute adenoiditis.
Each of these inflammations has distinctive characteristics, therefore only the general characteristics will be described.
Acute palatine tonsillitis and acute catarrhal lingual tonsillitis generally result from cases of cooling. The exception is the peritonsillar abscess, for which we speak of poor oral hygiene. They are all caused by a bacterial proliferation (streptococcus, pneumococcus and staphylococcus) at the local level, usually in the crypts. Symptoms can be observed in those who contract these inflammations. such as: fever, cough, pain in swallowing, hypertrophy (ie enlargement) of the tonsils and yellowing of the tonsillar tissue, whereas suppurative lingual tonsillitis, on the other hand, is caused by a foreign body.
Acute adenoiditis deserves more attention, as it usually affects infants and children. In fact, starting from 12-14 years of age, the pharyngeal tonsil begins a process of involution. The triggering cause is the proliferation of germs in the nasopharynx The most significant symptom is difficulty in breathing, which is more intense in infants than in children.
Finally, a non-serious pathological condition, as it is of non-bacterial origin, is cryptic-caseous halitosis. It occurs on the palatine tonsils and affects adolescents more for a reason closely linked to the process of atrophy of the tonsils: in fact, to the reduction of the lymphoid tissue does not correspond to a simultaneous reduction of the scaffolding of the crypts. As a result, the crypts are empty and food lurks inside. This is followed by a process of putrefaction, which manifests itself in bad breath. The tonsils become yellowish, but the symptoms of pain and fever are absent.