Low-power microscope magnification of a cross-section through one of the tonsillar crypts (running diagonally) as it opens onto the surface of the throat (at the top). Stratified epithelium (e) covers the throat's surface and continues as a lining of the crypt. Beneath the surface are numerous nodules (f) of lymphoid tissue. Many lymph cells (dark-colored region) pass from the nodules toward the surface and will eventually mix with the saliva as salivary corpuscles (s).
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The human palatine tonsils (PT) are covered by stratified squamous epithelium that extends into deep and partly branched tonsillar crypts, of which there are about 10 to 30. cm2, in addition to the 45 cm2 of epithelium covering the oropharyngeal surface.[ citation needed ]The crypts greatly increase the contact surface between environmental influences and lymphoid tissue. In an average adult palatine tonsil the estimated epithelial surface area of the crypts is 295
A stratified squamous epithelium consists of squamous (flattened) epithelial cells arranged in layers upon a basal membrane. Only one layer is in contact with the basement membrane; the other layers adhere to one another to maintain structural integrity. Although this epithelium is referred to as squamous, many cells within the layers may not be flattened; this is due to the convention of naming epithelia according to the cell type at the surface. In the deeper layers, the cells may be columnar or cuboidal. There are no intercellular spaces. This type of epithelium is well suited to areas in the body subject to constant abrasion, as the thickest layers can be sequentially sloughed off and replaced before the basement membrane is exposed. It forms the outermost layer of the skin and the inner lining of the mouth, esophagus and vagina.
The crypts extend through the full thickness of the tonsil reaching almost to its hemicapsule. In healthy tonsils the openings of the crypts are fissure-like, and the walls of the lumina are in apposition. A computerized three-dimensional reconstruction of the palatine tonsil crypt system showed that in the centre of the palatine tonsil are tightly packed ramified crypts that join with each other, while on the periphery there is a rather simple and sparse arrangement.[ citation needed ]
In biology, a lumen is the inside space of a tubular structure, such as an artery or intestine. It comes from Latin lumen, meaning 'an opening'.
The crypt system is not merely a group of invaginations of the tonsillar epithelium but a highly complicated network of canals with special types of epithelium and with various structures surrounding the canals, such as blood and lymphatic vessels and germinal centers.[ citation needed ]
In developmental biology, invagination is a mechanism that takes place during gastrulation. This mechanism or cell movement happens mostly in the vegetal pole. Invagination consists of the folding of an area of the exterior sheet of cells towards the inside of the blastula. In each organism, the complexity will be different depending on the number of cells. Invagination can be referenced as one of the steps of the establishment of the body plan. The term, originally used in embryology, has been adopted in other disciplines as well. There is more than one type of movement for invagination. Two common types are axial and orthogonal. The difference between the production of the tube formed in the cytoskeleton and extracellular matrix. Axial can be formed at a single point along the axis of a surface. Orthogonal is linear and trough.
Macrophages and other white blood cells concentrate by the tonsillar crypts as well, in response to the microorganisms attracted to the crypts. Accordingly, the tonsillar crypts serve a forward sentry role for the immune system, by providing early exposure of immune system cells to infectious organisms which may be introduced into the body via food or other ingested matter.[ citation needed ]
The immune system is a host defense system comprising many biological structures and processes within an organism that protects against disease. To function properly, an immune system must detect a wide variety of agents, known as pathogens, from viruses to parasitic worms, and distinguish them from the organism's own healthy tissue. In many species, the immune system can be classified into subsystems, such as the innate immune system versus the adaptive immune system, or humoral immunity versus cell-mediated immunity. In humans, the blood–brain barrier, blood–cerebrospinal fluid barrier, and similar fluid–brain barriers separate the peripheral immune system from the neuroimmune system, which protects the brain.
However, the tonsillar crypts often provide such an inviting environment to bacteria that bacterial colonies may form solidified "plugs" or "stones" within the crypts. In particular, sufferers of chronic sinusitis or post-nasal drip frequently suffer from these overgrowths of bacteria in the tonsillar crypts.[ medical citation needed ] These small whitish plugs, termed "tonsilloliths" and sometimes known as "tonsil stones," have a foul smell and can contribute to bad breath; furthermore, they can obstruct the normal flow of pus from the crypts, and may irritate the throat (people with tonsil stones may complain of the feeling that something is stuck in their throat).[ citation needed ]
Bacteria are a type of biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods and spirals. Bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit soil, water, acidic hot springs, radioactive waste, and the deep portions of Earth's crust. Bacteria also live in symbiotic and parasitic relationships with plants and animals. Most bacteria have not been characterised, and only about half of the bacterial phyla have species that can be grown in the laboratory. The study of bacteria is known as bacteriology, a branch of microbiology.
Sinusitis, also known as a sinus infection or rhinosinusitis, is inflammation of the mucous membrane that lines the sinuses resulting in symptoms. Common symptoms include thick nasal mucus, a plugged nose, and facial pain. Other signs and symptoms may include fever, headaches, poor sense of smell, sore throat, and cough. The cough is often worse at night. Serious complications are rare. It is defined as acute sinusitis if it lasts less than 4 weeks, and as chronic sinusitis if it lasts for more than 12 weeks.
Post-nasal drip occurs when excessive mucus is produced by the nasal mucosa. The excess mucus accumulates in the back of the nose and eventually the throat once it drips down the back of the throat. It can be caused by rhinitis, sinusitis, gastroesophageal reflux disease (GERD), or by a disorder of swallowing. Other causes can be allergy, cold, flu, and side effects from medications.
The large intestine, also known as the large bowel, is the last part of the gastrointestinal tract and of the digestive system in vertebrates. Water is absorbed here and the remaining waste material is stored as feces before being removed by defecation.
The gastrointestinal tract is an organ system within humans and other animals which takes in food, digests it to extract and absorb energy and nutrients, and expels the remaining waste as feces. The mouth, esophagus, stomach and intestines are part of the gastrointestinal tract. Gastrointestinal is an adjective meaning of or pertaining to the stomach and intestines. A tract is a collection of related anatomic structures or a series of connected body organs.
A lymph node or lymph gland is an ovoid or kidney-shaped organ of the lymphatic system, and of the adaptive immune system, that is widely present throughout the body. They are linked by the lymphatic vessels as a part of the circulatory system. Lymph nodes are major sites of B and T lymphocytes, and other white blood cells. Lymph nodes are important for the proper functioning of the immune system, acting as filters for foreign particles and cancer cells. Lymph nodes do not have a detoxification function, which is primarily dealt with by the liver and kidneys.
In humans and most mammals and birds, the iris is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupil and thus the amount of light reaching the retina. Eye color is defined by that of the iris. In optical terms, the pupil is the eye's aperture, while the iris is the diaphragm.
Palatine tonsils, commonly called the tonsils and occasionally called the faucial tonsils, are tonsils located on the left and right sides at the back of the throat, which can often be seen as flesh-colored, pinkish lumps. Tonsils only present as "white lumps" if they are inflamed or infected with symptoms of exudates and severe swelling.
The adenoid, also known as a pharyngeal tonsil or nasopharyngeal tonsil, is the superior-most of the tonsils. It is a mass of lymphatic tissue located behind the nasal cavity, in the roof of the nasopharynx, where the nose blends into the throat. In children, it normally forms a soft mound in the roof and back wall of the nasopharynx, just above and behind the uvula.
Tonsillitis is inflammation of the tonsils, typically of rapid onset. It is a type of pharyngitis. Symptoms may include sore throat, fever, enlargement of the tonsils, trouble swallowing, and large lymph nodes around the neck. Complications include peritonsillar abscess.
Peyer's patches are organized lymphoid follicles, named after the 17th-century Swiss anatomist Johann Conrad Peyer. They are an important part of gut associated lymphoid tissue usually found in humans in the lowest portion of the small intestine, mainly in the distal jejunum and the ileum, but also could be detected in the duodenum.
Tonsilloliths, also known as tonsil stones, are soft aggregates of bacterial and cellular debris that form in the tonsillar crypts, the crevices of the tonsils. While they occur most commonly in the palatine tonsils, they may also occur in the lingual tonsils. Tonsil stones are common. Tonsilloliths have been recorded weighing from 0.3 g to 42 g.
The lingual tonsils are two small mounds of lymphatic tissue located at the back of the base of the tongue, one on either side. They are composed of lymphatic tissue that functions to assist the immune system in the production of antibodies in response to invading pathogenic bacteria or viruses.
Gut-associated lymphoid tissue (GALT) is a component of the mucosa-associated lymphoid tissue (MALT) which works in the immune system to protect the body from invasion in the gut.
The innate immune system is one of the two main immunity strategies found in vertebrates. The innate immune system is an older evolutionary defense strategy, relatively speaking, and it is the dominant immune system response found in plants, fungi, insects, and primitive multicellular organisms.
The mucosa-associated lymphoid tissue (MALT), also called mucosa-associated lymphatic tissue, is a diffuse system of small concentrations of lymphoid tissue found in various submucosal membrane sites of the body, such as the gastrointestinal tract, oral passage, nasopharyngeal tract, thyroid, breast, lung, salivary glands, eye, and skin. MALT is populated by lymphocytes such as T cells and B cells, as well as plasma cells and macrophages, each of which is well situated to encounter antigens passing through the mucosal epithelium. In the case of intestinal MALT, M cells are also present, which sample antigen from the lumen and deliver it to the lymphoid tissue.
Paneth cells are one of the principal cell types of the epithelium of the small intestine, along with goblet cells, enterocytes, and enteroendocrine cells. They are identified microscopically by their location just below the intestinal stem cells in the intestinal glands and the large eosinophilic refractile granules that occupy most of their cytoplasm. These granules consist of several anti-microbial compounds and other compounds that are known to be important in immunity and host-defense. When exposed to bacteria or bacterial antigens, Paneth cells secrete some of these compounds into the lumen of the intestinal gland, thereby contributing to maintenance of the gastrointestinal barrier.
In histology, an intestinal gland is a gland found in the intestinal epithelium lining of the small intestine and large intestine (colon). The glands and intestinal villi are covered by epithelium, which contains multiple types of cells: enterocytes, goblet cells, enteroendocrine cells, cup cells, tuft cells, and at the base of the gland, Paneth cells and stem cells. These cells are not all present in the colon.
This article describes the anatomy of the head and neck of the human body, including the brain, bones, muscles, blood vessels, nerves, glands, nose, mouth, teeth, tongue, and throat.
Waldeyer's tonsillar ring is a ringed arrangement of lymphoid tissue in the pharynx. Waldeyer's ring surrounds the naso- and oropharynx, with some of its tonsillar tissue located above and some below the soft palate.
Tonsils are collections of lymphoid tissue 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.
The pharynx is the part of the throat behind the mouth and nasal cavity and above the esophagus and larynx, or the tubes going down to the stomach and the lungs. It is found in vertebrates and invertebrates, though its structure varies across species.
Carcinoma of the tonsil is a type of squamous cell carcinoma. The tonsil is the most common site of squamous cell carcinoma in the oropharynx. The tumors frequently present at advanced stages, and around 70% of patients present with metastasis to the cervical lymph nodes. . The most reported complaints include sore throat, otalgia or dysphagia. Some patients may complain of feeling the presence of a lump in the throat. Approximately 20% patients present with a node in the neck as the only symptom.
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