Schwann cell Health Dictionary

Schwann Cell: From 1 Different Sources


The cells that produce the MYELIN sheath of the AXON of a medullated NERVE. They are wrapped around a segment of the axon, forming concentric layers.
Health Source: Medical Dictionary
Author: Health Dictionary

Basal Cell Carcinoma

A generally slow growing malignant epithelial tumour, which has potential to invade and metastasise, especially if untreated.... basal cell carcinoma

Cellulitis

In?ammation taking place in cellular tissue, and usually referring to infection in the subcutaneous tissue. A related word, cellulite, which has no medical meaning, is used in the slimming business to refer to excess fatty tissue in the arms, buttocks and thighs. (See ABSCESS; ERYSIPELAS.)... cellulitis

Cell

The smallest unit of living material that can function independently.... cell

Germ Cell

Those embryonic cells with the potential to develop into ova (see OVUM) or spermatozoa (see SPERMATOZOON).... germ cell

Renal Cell Carcinoma

See HYPERNEPHROMA.... renal cell carcinoma

Squamous Cell Carcinoma

Malignant tumour of squamous epithelium of skin, which generally spreads and metastasises.... squamous cell carcinoma

Stem Cell

Stem CELLS develop a few days after an egg (ovum) is fertilised by a spermatozoon and starts developing to form an EMBRYO. These master cells are crucial to the development of a normal embryo. They contain a specialised ENZYME that gives them the facility to divide inde?nitely, developing into the many di?erent specialised cells that comprise the various tissues in the body – for example, skin, blood, muscle, glands or nerves.

In a highly signi?cant advance in research, a scienti?c team in the United States obtained stem cells from newly formed human embryos

– donated by women who had become pregnant after successful in vitro fertilisation – and successfully cultivated these cells in the laboratory. This achievement opened the way to replicating in the laboratory, the various specialised cells that develop naturally in the body. UK government legislation constrains the use of human embryos in research (see ETHICS) and the ethical aspects of taking this stem-cell culture technique forwards will have to be resolved. Nevertheless, this discovery points the biological way to the use of genetic engineering in selecting di?erentiated specialised cells from which replacement tissues could be grown for use as transplants to rectify absent or damaged tissues in the human body.

Research into potential use of stem cells has raised expectations that in the long term they may prove to be an e?ective regenerative treatment for a wide range of disorders including PARKINSONISM, ALZHEIMER’S DISEASE, type-2 diabetes (see under DIABETES MELLITUS), myocardial infarction (see HEART, DISEASES OF), severe burns, osteoporosis (see under BONE, DISORDERS OF) and the regeneration of blood to replace the need for BONE MARROW TRANSPLANT. Recent research has shown that adult stem cells may also be stimulated to produce new cell lines. If successful, this would eliminate the need to use embryos and thus resolve existing ethical dilemmas over the use of stem cells.... stem cell

Giant Cell Arteritis

See: ARTERITIS. ... giant cell arteritis

Cellulose

A carbohydrate substance forming the skeleton of most plant structures. It is colourless, transparent, insoluble in water and is practically unaffected by digestion. In vegetable foods it therefore adds to the bulk, but it is of no value as a food-stu?. It is found in practically a pure state in cotton-wool.... cellulose

Goblet Cell

A columnar secretory cell occurring in the EPITHELIUM of the respiratory and intestinal tracts.

The cells produce the main constituents of MUCUS.... goblet cell

Haemopoietic Stem Cell

This is the basic cell from which all types of blood cells originate. Its appearance is believed to be similar to that of a LYMPHOCYTE.... haemopoietic stem cell

Interstitial Cells

Also called Leydig cells, these cells are scattered between the SEMINIFEROUS TUBULES of the testis (see TESTICLE). LUTEINISING HORMONE from the anterior PITUITARY GLAND stimulates the interstitial cells to produce androgens, or male hormones.... interstitial cells

Kupffer Cells

Star-shaped cells present in the blood-sinuses of the LIVER. They form part of the RETICULOENDOTHELIAL SYSTEM and are to a large extent responsible for the breakdown of HAEMOGLOBIN into the BILE pigments.... kupffer cells

Mast Cells

These are a group of cells that line the capillaries of tissues that come in contact with the outside, like skin, sinuses, and lung mucosa. They, like their first cousin basophils, are produced in the red bone marrow and migrate to the appropriate tissues, where they stay. They bind IgE, supply the histamine and heparin response that gives you a healing inflammation, and cause allergies.... mast cells

Nerve Cell

See NEURON(E).... nerve cell

Oat Cell

A type of cell found in one highly malignant form of lung cancer. The cell is small and either oval or round. The nucleus stains darkly and the cytoplasm is sparse and di?cult to identify. Oat-cell, or small-cell, carcinoma of the bronchus is usually caused by smoking, and comprises around 30 per cent of all bronchial cancers. It responds to radiotherapy and chemotherapy but, because the growth has usually spread widely by the time it is diagnosed, the prognosis is poor. Results of surgery are unsatisfactory.... oat cell

Packed Cell Volume

That fraction of the blood’s total volume made up of red cells. The packed cell volume is found by centrifuging blood in a tube and measuring the depth of the column of red cells as a fraction of the whole column of blood. (See also HAEMATOCRIT.)... packed cell volume

Plasma Cells

These are cells that produce ANTIBODIES and occur in bone-forming tissue as well as the lining of the gastrointestinal tract and the lungs. The cells develop in LYMPH NODES, SPLEEN and BONE MARROW when T-lymphocytes (see IMMUNITY) are stimulated by antigens (see ANTIGEN) to produce the precursor cells from which plasma cells originate.... plasma cells

Purkinje Cells

Large specialised nerve cells occurring in great numbers in the cortex (super?cial layer of grey matter) of the cerebellum of the BRAIN. They have a ?ask-shaped body, an AXON and branching tree-like extensions called dendrites, which extend towards the surface of the brain (see NEURON(E)).... purkinje cells

Red Blood Cell

See ERYTHROCYTES; BLOOD.... red blood cell

Small-cell Carcinoma

See OAT CELL.... small-cell carcinoma

T-cell

A specialised white cell (lymphocyte) responsible for cell-mediated immunity. See also T-lymphocyte.... t-cell

Target Cell

Abnormal ERYTHROCYTES which are large and ‘?oppy’ and have a ringed appearance, similar to that of a target, when stained and viewed under the microscope. This change from normal may occur with iron-de?ciency ANAEMIA, liver disease, a small SPLEEN, haemoglobinopathies (disorders of HAEMOGLOBIN), and THALASSAEMIA.

A target cell is also a cell that is the focus of attack by macrophages (killer cells – see MACROPHAGE) or ANTIBODIES; it may also be the site of action of a speci?c hormone (see HORMONES).... target cell

White Blood Cell

See LEUCOCYTES.... white blood cell

Cellulite

Not a medical term. Puffy skin from deposition of fat. “Orange peel skin”. Occurs chiefly in women as lumpy flesh on buttocks, thighs, stomach, knees and upper arm. Though not due to increased fluid in the tissues, it is sufficient to arrest the circulation. Constriction of capillaries causes toxic wastes to build up, forming nodules that lock away fat in the tissues. Hormone imbalance also suspected. Varicose veins may appear with cellulite from poorly supportive connective tissue. Usual cause: poor posture and unhealthy lifestyle.

Treatment. To activate capillary function and assist toxic elimination: Bladderwrack, Gotu Kola, Kola, Parsley tea. A diuretic may assist by eliminating excess fluid.

Gotu Kola tea: Quarter to half a teaspoon leaves to each cup boiling water; infuse 5-10 minutes. 1 cup morning and evening.

Formula. Tea. Equal parts: Alfalfa, Clivers, Fennel, Senna leaves. 1 heaped teaspoon to each cup boiling water: infuse 5-10 minutes. Half-1 cup morning and evening.

Seline. Tablets. Ingredients: Each tablet contains Lecithin 100mg; Pulverised Dandelion 100mg; Pulverised Horsetail 100mg; Pulverised extract Fucus 5:1 30mg; Vitamin C 40mg; Vitamin B6 1mg. 1 tablet thrice daily.

Aescin. Compound isolated from Horse-chestnuts to decrease capillary permeability and swelling. Topical. Decoction of Horse-chestnuts as a lotion. Or: infusion of Bladderwrack.

Aromatherapy and Herb essences. Combination for external use. Ingredients: Almond oil 47ml; Fennel oil 1ml; Juniper oil 1ml; Cypress essence 0.5ml; Lemon essence 0.5ml. Apply to affected areas morning and evening; small area 5 drops, large area 10 drops (Gerard). Gentle massage with a string glove, loofah or massage glove.

Diet. Reduce calorie intake. Raw fresh fruits and vegetable salads to account for 50 per cent of the diet. No sweet or dried fruits. Conservatively-cooked vegetables. Seafood. Iodine-rich foods. Wholegrain cereals. Protein: beans, chicken, poached eggs, fish, little lean meat: no pork, bacon or ham. Low-fat yoghurt. Cold-pressed unsaturated oils for salad dressings with lemon juice. Dandelion coffee to stimulate liver. Avoid sugar, alcohol, bananas and white flour products. Spring water.

Supportives. Stop smoking. Adopt an alternative to the contraceptive pill. To avoid fluid retention, 2-3 glasses of water daily. ... cellulite

B-cell

See lymphocyte.... b-cell

Cell Division

The processes by which cells multiply. Mitosis is the most common form of cell division, giving rise todaughter cells identical to the parent cells.

Meiosis produces egg (see ovum) and sperm cells that differ from their parent cells in that they have only half the normal number of chromosomes.... cell division

Germ Cell Tumour

A growth comprised of immature sperm cells in the male testis or of immature ova in the female ovary. A seminoma is one type of germ cell tumour (see testis, cancer of).... germ cell tumour

Mast Cell

A type of cell that plays an important part in allergy.

In an allergic response, mast cells release histamine.... mast cell

B-lymphocyte (or B-cell)

A type of white blood cell that circulates through the body and is able to detect the presence of the foreign agents. Once exposed to an antigen on the agent, these cells differentiate into plasma cells to produce antibody.... b-lymphocyte (or b-cell)

Cell Salvage Transfusion

See TRANSFUSION.... cell salvage transfusion

Cell-mediated Immunity

A defence mechanism involving the coordinated activity of two subpopulations of TLymphocytes, helper T-Cells and killer T-Cells. Helper T-Cells produce a variety of substances that stimulate and regulate other participants in the immune response. Killer T-Lymphocytes destroy cells in the body that bear foreign antigens (e.g. cells that are infected with viruses or other microorganisms).... cell-mediated immunity

Cells

The basic structural unit of body tissues. There are around 10 billion cells in the human body and they are structurally and functionally linked to carry out the body’s many complex activities.

Every cell consists essentially of a cell-body of soft albuminous material called cytoplasm, in which lies a kernel or nucleus which seems to direct all the activities of the cell. Within the nucleus may be seen a minute body, the nucleolus; and there may or may not be a cell-envelope around all. (See also MITOCHONDRIA.) Each cell nucleus carries a set of identical CHROMOSOMES, the body’s genetic instructions.

Cells vary much in size, ranging in the human body from 0·0025 mm to about 0·025 mm.

All animals and plants consist at ?rst of a single cell (the egg-cell, or ovum), which begins to develop when fertilised by the sperm-cell derived from the opposite sex. Development begins by a division into two new cells, then into four, and so on till a large mass is formed. These cells – among them stem cells (see STEM CELL) which have the potential to develop into a variety of specialised cells – then arrange themselves into layers, and form various tubes, rods, and masses which represent in the embryo the organs of the fully developed animal. (See FETUS.)

When the individual organs have been laid down on a sca?olding of cells, these gradually change in shape and in chemical composition. The cells in the nervous system send out long processes to form the nerves; those in the muscles become long and striped in appearance; and those which form fat become ?lled with fat droplets which distend the cells. Further, they begin to produce, between one another, the substances which give the various tissues their special character. Thus, in the future bones, some cells deposit lime salts and others form cartilage, while in tendons they produce long white ?bres of a gelatinous substance. In some organs the cells change little: thus the liver consists of columns of large cells packed together, while many cells, like the white blood corpuscles, retain their primitive characters almost entire.

Thus cells are the active agents in forming the body, and they have a similar function in repairing its wear and tear. Tumours, and especially malignant tumours, have a highly cellular structure, the cells being of an embryonic type, or, at best, forming poor imitations of the tissues in which they grow (see TUMOUR).... cells

Mesenchymal Cells

Literally, those derived from embryonic mesoderm; practically, those in a tissue that give it structure and form. The opposite of parenchymal.... mesenchymal cells

Perioperative Cell Salvage

A method of autologous blood TRANSFUSION – using a patient’s own blood, salvaged during a surgical operation – instead of conventional blood-bank transfusion.... perioperative cell salvage

Peripheral-blood Stem-cell Transplants

These have almost completely replaced BONE MARROW TRANSPLANT, used to treat malignancies such as LEUKAEMIA and LYMPHOMA for the past 20 years. The high doses of CHEMOTHERAPY or RADIOTHERAPY used to treat these diseases destroy the bone marrow which contains stem cells from which all the blood cells derive. In 1989 stem cells were found in the blood during recovery from chemotherapy. By giving growth factors (cytokines), the number of stem cells in the blood increased for about three to four days. In a peripheral-blood stem-cell transplant, these cells can be separated from the peripheral blood, without a general anaesthetic. The cells taken by either method are then frozen and returned intravenously after the chemotherapy or radiotherapy is completed. Once transplanted, the stem cells usually take less than three weeks to repopulate the blood, compared to a month or more for a bone marrow transplant. This means that there is less risk of infection or bleeding during the recovery from the transplant. The whole procedure has a mortality risk of less than 5 per cent – half the risk of a bone marrow transplant.... peripheral-blood stem-cell transplants

T-cell Lymphoma

See LYMPHOMA.... t-cell lymphoma

T-helper Cells

A type of lymphocyte which assists the B-Lymphocytes in producing antibodies.... t-helper cells

T-lymphocytes (or T-cells)

White blood cells that have matured in the thymus gland. There are at least two kinds of T-lymphocytes - helpers and suppressors. In AIDS, the number of helper cells is decreased.... t-lymphocytes (or t-cells)

T-suppressor Cells

A type of T-lymphocyte that stops antibody production when the invading antigen has been inactivated.... t-suppressor cells

Tea For Cellulite

Cellulite is a painless affection which consists of the fat layer growth. This is not very unusual and many women around the world suffer from it. Generally, cellulite is your body’s way of protecting your organism when you’re pregnant. On the other hand, you can develop cellulite from having a very unbalanced diet: unhealthy foods and drinks (sodas and fast food). Also, the lack of workout and exercise will slow your calories from burning, making them stick mostly to your hips and thighs. How Tea for Cellulite Works A Tea for Cellulite’s main purpose is to make your blood veins work properly and eliminate the lipids surplus. Also, their action implies veins dilatation and increased blood pressure so that your entire body will work to get rid of the unwanted fats. What you need to know about cellulite is that this is not regular fat and, at times, even thin women have it. Keeping a diet will not make it go away so don’t starve yourself to death! Efficient Tea for Cellulite When choosing a Tea for Cellulite, you must keep in mind a couple of facts: it must be very efficient and safe. Since having a cellulite will not hurt more than your feelings, alternative medicine practitioners advice against all pills that promise to work miracles on your body and recommend, instead, an herbal treatment. If you don’t know which teas to choose from, here’s a list to guide you on: - Horse Chestnut Tea – it has anti inflammatory properties. Its main active constituent, Aescin, improves your blood flow by decreasing the pore size of your capillary walls. This will make your skin look a lot smoother and reduce the cellulite level. - Ginkgo Biloba Tea – is a great vasodilator whose main goal is to improve circulation. This Tea for Cellulite will also stop cholesterol level from enhancing and it can be used to treat memory loss, stress, anxiety, headaches and anemia. However, don’t drink more than 3 cups per day or you’ll get diarrhea. - Green Tea – has blood thinning properties, so you must avoid it at all costs in case you’re already on regular blood thinners. A cup of Green Tea per day will also improve your general health and bring relief in case you’re suffering from infertility, anemia, headaches or stress. However, don’t take it if you’re on menopause or menstruation in order to avoid stomach irritations and uterine contractions. - Dandelion Tea – will enhance your liver’s ability to process lipids faster and energize your entire body. However, this Tea for Cellulite is also a strong diuretic and purgative so you may want to avoid it if you suffer from diarrhea or upset stomach. Also, too much dandelion tea might cause urinary tract infections. Tea for Cellulite Side Effects When taken properly, these teas are generally safe. However, exceeding the number of cups recommended per day may weaken your digestive and nervous systems and lead to vomiting, nausea, headaches and even hallucinations. Before starting a treatment based on a Tea for Cellulite, talk to your doctor in order to find out which are the risks. Don’t take any of these teas if you’re pregnant, breastfeeding, on blood thinners, anticoagulants or preparing for a surgery. Children shouldn’t be allowed to take an herbal treatment since there is no study to prove how safe it is for them. But if you have the green light from your doctor and nothing could interfere with your Tea for Cellulite cure, choose a tea that fits best your needs and enjoy its health benefits!... tea for cellulite

Anaemia: Sickle Cell

A form of anaemia growing into an acute social problem, affecting people of African, Asian, and Mediterranean origin. Thalassaemias are caused by defects of a gene that produces the globin part of haemoglobin. Such defects in the DNA can now be detected in the womb before birth. The name derives from sickle-shaped cells instead of circular red blood cells. Few sufferers survive beyond their 40th year.

Symptoms. Unhealthy pallor, listlessness, sore tongue, dizziness, vague aches and pains, rapid pulse and breathing, tinnitus, palpitation. The skull may be disproportionately large, resistance to infection feeble, chances of survival poor. This form of anaemia is linked with defective colour vision. Impaired liver function. Stunted growth, great pain. Sufferers have a higher risk of infection.

Malaria. Sufferers are less likely to die of malaria because their red cells do not support the growth of malaria parasites very well.

Carriers: Carriers of the sickle-cell gene can now be identified by a simple blood test.

Treatment. No specifics exist but supportive herbal treatment has been known to increase output of red cells and raise haemoglobin levels:– Red Clover flowers, Yellow Dock, Echinacea, Burdock, Wild Indigo, Gentian, Nettles, Birch leaves, Sage, Walnut leaves, Centaury, Gota Kola (Indian Pennywort). Alternatives:– Tea. Mix equal parts: Iceland Moss, Nettles, Red Clover flowers. 2 teaspoons to each cup boiling water; infuse 15 minutes; 1 cup morning and evening.

Decoction. Mix equal parts; Echinacea, Walnut leaves, Balm of Gilead buds; 1 teaspoon to each cup water gently simmered for 20 minutes. Half-1 cup, cold, 3 times daily, before meals.

Tablets/capsules. Sarsaparilla. Ginseng. Iceland Moss. Red Clover. Echinacea. Gentian.

Powders. Formula: Echinacea 1; Fringe Tree half; Ginseng half; White Poplar bark 1. Dose: 500mg (two 00 capsules or one-third teaspoon) thrice daily before meals.

Liquid extracts. Formula. Echinacea 2; Dandelion 1; Oat Husk (avena sativa) 1. Mix. Dose, 1-2 teaspoons before meals, in water or one of the above teas or decoctions.

Tinctures. Same combination. Dose: 2-3 teaspoons.

Dong quai. See entry.

Pollen. Claimed to be of value.

Diet. Dandelion coffee. Molasses. Desiccated liver. Calf liver, fresh. Green leafy vegetables contain chlorophyll, iron and folic acid. Cider vinegar. Dried beans, apricots and shellfish. Dandelion leaves in salads. Milk, eggs, meats, Soya. Carrot juice to increase red cells.

Supplements. Daily. Vitamin B12. Vitamin C, 1g; Folic acid 400mcg, Floradix. Of particular value: Vitamin E 400iu. Zinc.

Note: Those at risk should submit themselves for screening. The disease cannot be cured but can be controlled largely by orthodox measures and sometimes by natural medicine. ... anaemia: sickle cell

Cancer – Squamous Cell Carcinoma

Given three months to live, Jason Winters, terminal cancer patient, was suffering from infiltrating squamous cell carcinoma wrapped round his carotid artery. Refusing major surgery, he travelled the world in search of native remedies. He was able to contact people who put him on the track of Wild Violet leaves, Red Clover flowers (Trifolium pratense) and leaves of the Chaparral bush (Larrea divaricata). The story of how he infused them, together with a well- known spice, is dramatically recorded in his book “Killing Cancer”. After a spectacular recovery, remission has lasted for over 15 years and others have benefited from his experience.

Treatment by oncologist. ... cancer – squamous cell carcinoma

Apud Cell Tumour

A growth composed of cells that produce various hormones. These cells, amine precursor uptake and decarboxylation (APUD) cells, occur in different parts of the body. Some tumours of the thyroid gland, pancreas, and lungs are cell tumours, as are a carcinoid tumour (see carcinoid syndrome) and phaeochromocytoma (a type of adrenal tumour).... apud cell tumour

Blood Cells

Cells, also called blood corpuscles, present in blood for most or part of their lifespan. They include red blood cells, which make up about 45 per cent by volume of normal blood, white blood cells, and platelets. Blood cells are made in the bone marrow by a series of divisions from stem cells.

Red blood cells (also known as RBCs, red blood corpuscles, or erythrocytes) transport oxygen from the lungs to the tissues (see respiration). Each is packed with haemoglobin, enzymes, minerals, and sugars. Abnormalities can occur in the rate at which RBCs are either produced or destroyed, in their numbers, and in their shape, size, and haemoglobin content, causing forms of

anaemia and polycythaemia (see blood, disorders of).

White blood cells (also called WBCs, white blood corpuscles, or leukocytes) protect the body against infection and fight infection when it occurs. The 3 main types of are granulocytes (also called polymorphonuclear leukocytes), monocytes, and lymphocytes. Granulocytes are further classified as neutrophils, eosinophils, or basophils, and each type of granulocyte has a role in either fighting infection or in inflammatory or allergic reactions. Monocytes and lymphocytes also play an important part in the immune system. Lymphocytes are usually formed in the lymph nodes. One type, a T-lymphocyte, is responsible for the delayed hypersensitivity reactions

White (see allergy) and Red blood blood cell is also involved in cell (neutrophil) protection against cancer. T-lymphocytes manufacture chemicals, known as lymphokines, which affect the function of other cells. In addition, the T-cells moderate the activity of B-lymphocytes, which form the antibodies that can prevent a second attack of certain infectious diseases. Platelets (also known as thrombocytes), are the smallest blood cells and are important in blood clotting.

The numbers, shapes, and appearance of the various types of blood cell are of great value in the diagnosis of disease (see blood count; blood film).... blood cells

Orbital Cellulitis

Bacterial infection of the tissues within the eye socket, or orbit.

Infection is potentially serious as it may spread to the brain.

Treatment is with high doses of antibiotic drugs.... orbital cellulitis

Pathology, Cellular

Also called cytopathology, the branch of cytology concerned with the effects of disease on cells.... pathology, cellular

Sickle Cell Anaemia

An inherited blood disease in which the red blood cells contain haemoglobin S, an abnormal type of haemoglobin. This crystallizes in the capillaries, making red cells sickle-shaped and fragile, and leading to haemolytic anaemia. The abnormal cells are unable to pass easily through tiny blood vessels. The blood supply to organs is blocked intermittently, causing sickle cell crises. The disease affects mainly black people.Symptoms usually appear after age 6 months, often beginning with painful swelling of the hands and feet. Chronic haemolytic anaemia causes fatigue, headaches, shortness of breath on exertion, pallor, and jaundice. Sickle cell crises start suddenly; they are sometimes brought on by an infection, cold weather, or dehydration, but may also occur for no apparent reason. The sufferer may experience pains (especially in the bones), blood in the urine (from kidney damage) or damage to the lungs or intestines. If the brain is affected, seizures, a stroke, or unconsciousness may result.

In some affected children, the spleen enlarges and traps red cells at a particularly high rate, causing a life-threatening form of anaemia. After adolescence, the spleen usually stops functioning, increasing the risk of infection in those affected.

Diagnosis is made from examination of a blood smear and electrophoresis.

Supportive treatment may include folic acid supplements, and penicillin and immunization to protect against infection.

Life-threatening crises are treated with intravenous infusions of fluids, antibiotics, oxygen therapy, and analgesic drugs.

If the crisis still does not respond, an exchange blood transfusion may be performed.

This may be done regularly for people who suffer frequent severe crises.... sickle cell anaemia

Antigen-presenting Cell

(APC) a cell, such as a *dendritic cell or a *macrophage, that processes antigen for presentation to a T lymphocytes (see helper T cell).... antigen-presenting cell

Apud Cells

cells that share the metabolic property of amine-precursor uptake and decarboxylation. They have a wide distribution, especially in the mucosa of the gastrointestinal tract and pancreas, and their function is to synthesize and release polypeptides that serve as regulator peptides and neurotransmitters. They are often known as the diffuse neuroendocrine system.... apud cells

Argentaffin Cells

cells that stain readily with silver salts. Such cells occur, for example, in the crypts of Lieberkühn in the intestine.... argentaffin cells

Askanazy Cells

see Hürthle cell tumour.... askanazy cells

Beta Cells

see islets of Langerhans.... beta cells

Blood Cell

(blood corpuscle) any of the cells that are present in the blood in health or disease. The cells may be subclassified into three major categories, namely red cells (*erythrocytes); white cells (*leucocytes), which include granulocytes, lymphocytes, and monocytes; and *platelets (see illustration). The blood cells account for approximately 40% of the total volume of the blood in health; red cells comprise the vast majority.... blood cell

Burr Cell

(echinocyte) a red blood cell (erythrocyte) with abnormal small thorny projections. See crenation.... burr cell

C Cells

parafollicular cells of the thyroid gland, which are derived from neural crest tissue. They produce *calcitonin. *Medullary carcinoma of the thyroid has its origin in the C cells.... c cells

Cell Body

(perikaryon) the enlarged portion of a *neuron (nerve cell), containing the nucleus. It is concerned more with the nutrition of the cell than with propagation of nerve impulses.... cell body

Cellophane Maculopathy

see epiretinal membrane.... cellophane maculopathy

Cell Saver

a machine that aspirates blood lost during surgery and immediately spins, washes, and filters it for retransfusion back into the patient’s body (see autotransfusion). The process, called intraoperative cell salvage, is used in surgery that has significant blood loss, such as orthopaedic and vascular surgery and Caesarean section, and avoids the costs and risks of *allogeneic transfusion.... cell saver

Cell-surface Molecules

molecules on the surface of cell membranes that are responsible for most cellular functions directly related to their immediate environment. Many have very precise functions of adhesion (see adhesion molecules), metabolic exchange, hormone reception, respiration, and immune reactions. Cell-to-cell exchanges involve specialized surface structures (junctions), which form a communicating nexus.... cell-surface molecules

Clear-cell Carcinoma

(clear-cell adenocarcinoma) a variant of *adenocarcinoma that tends to arise from the kidneys or the female genital tract. In the latter case it is linked to intrauterine exposure to *diethylstilbestrol during the 1950s and 1960s and takes the form of a vaginal cancer, which can be treated by radical surgery followed by radiotherapy.... clear-cell carcinoma

Cutaneous T-cell Lymphoma

a group of lymphomas in which abnormal T *lymphocytes are concentrated in the skin. The most common form is *mycosis fungoides.... cutaneous t-cell lymphoma

Cytotoxic T Cell

a type of T *lymphocyte that destroys cancerous cells, virus-infected cells, and *allografts. Cytotoxic T cells recognize peptide antigens attached to proteins that are encoded by the *HLA system.... cytotoxic t cell

D Cells

see islets of Langerhans.... d cells

Dendritic Cell

a type of haemopoietic cell with specialized antigen-presenting functions. The head and neck are common sites for dendritic cell pathology. See antigen-presenting cell.... dendritic cell

Egg Cell

see ovum.... egg cell

G-cell

n. any of the gastrin-secreting cells of the stomach lining located predominantly in the gastric *antrum. Gastrin stimulates the production of gastric acid by parietal cells in the stomach. Increased G-cell activity is associated with the formation of duodenal ulcers and the *Zollinger-Ellison syndrome.... g-cell

Giant Cell

any large cell, such as a *megakaryocyte. Giant cells may have one or many nuclei.... giant cell

Golgi Cells

types of *neurons (nerve cells) within the central nervous system. Golgi type I neurons have very long axons that connect different parts of the system; Golgi type II neurons, also known as microneurons, have only short axons or sometimes none.... golgi cells

Hairy Cell

an abnormal white blood cell that has the appearance of an immature lymphocyte with fine hairlike cytoplasmic projections around the perimeter of the cell. It is found in a rare form of leukaemia (hairy-cell leukaemia) most commonly occurring in young men.... hairy cell

Helper T Cell

a type of T *lymphocyte that plays a key role in cell-mediated immunity by recognizing foreign antigen on the surface of *antigen-presenting cells when this is associated with the individual’s *MHC antigens, having been processed by antigen-presenting cells. Helper T cells stimulate the production of *cytotoxic T cells, which destroy the target cells.... helper t cell

Hilar Cell Tumour

an androgen-producing tumour of the ovary found in older women and often resulting in *virilization. Such tumours are so called as they tend to occur around the area of the ovary where the blood vessels enter (the hilum). They are usually small and are treated by surgical removal, with resolution of most of the symptoms.... hilar cell tumour

Hürthle Cell Tumour

a malignant tumour of the thyroid gland that arises from Hürthle (or Askanazy) cells, altered follicular cells of the gland that have large nuclei and stain deeply with eosin (these cells are also found in benign nodules and Hashimoto’s disease). Hürthle cell carcinoma is not as common as papillary, follicular, or anaplastic thyroid carcinomas (see thyroid cancer). [K. W. Hürthle (1860–1945), German histologist]... hürthle cell tumour

Interstitial-cell-stimulating Hormone

see luteinizing hormone.... interstitial-cell-stimulating hormone

Islet Cell Antibodies

a group of autoantibodies directed against components of the insulin-secreting beta cells of the pancreas. They are usually detectable in the blood of people presenting with type 1 diabetes. Antibodies against *glutamic acid decarboxylase (GAD) in the beta cells have become a more specific test for islet cell antibodies, to help confirm a diagnosis of type 1 diabetes.... islet cell antibodies

Islet Cell Transplantation

a new technique still under evaluation for curing type 1 *diabetes mellitus, which involves the injection of donated cells from the pancreatic *islets of Langerhans into the liver, where it is hoped they will seed and survive. The transplanted cells then take over insulin production from the recipient’s diseased pancreas.... islet cell transplantation

Islet Cell Tumour

any tumour arising in a cell of the pancreatic *islets of Langerhans. These tumours, which include *insulinomas, *glucagonomas, and *somatostatinomas, form one of the two major subclasses of gastrointestinal neuroendocrine tumours, the other being the *carcinoid tumours.... islet cell tumour

Langerhans Cell Histiocytosis

overgrowth of cells of the *reticuloendothelial system. This includes disorders previously called histiocytosis X, including eosinophilic granuloma, Hand–Schüller–Christian disease, and Letterer–Siwe disease. [P. Langerhans (1847–88), German physician and anatomist]... langerhans cell histiocytosis

Leydig Cells

see interstitial cells. [F. von Leydig (1821–1908), German anatomist]... leydig cells

Memory Cell

a long-lived lymphocyte that is formed following primary infection. It enables a faster and more robust immune response following a second exposure to the antigen.... memory cell

Mesangial Cells

see juxtaglomerular apparatus.... mesangial cells

Natural Killer Cell

(NK cell) a type of *lymphocyte that is able to kill virus-infected cells and cancerous cells and mediates rejection of bone-marrow grafts. NK cells are a part of natural (or innate) *immunity. Their function is regulated by a balance between activating receptors, which recognize proteins on cancerous or virus-infected cells, and inhibitory receptors specific for certain molecules encoded by the *HLA system.... natural killer cell

Nk Cell

see natural killer cell.

nm symbol for *nanometre.... nk cell

Non-small-cell Lung Cancer

(NSCLC) any type of lung cancer other than *small-cell lung cancer. Such cancers include *adenocarcinoma of the lung, large-cell carcinomas, and squamous-cell carcinoma of the lung.... non-small-cell lung cancer

Onodi Cell

a posterior ethmoidal sinus air cell (see paranasal sinuses). They are surgically important because of their proximity to the optic nerve and internal carotid artery. [A. Onodi (1857–1919), Hungarian rhinolaryngologist]... onodi cell

Oxyntic Cells

see parietal cells.... oxyntic cells

Parietal Cells

(oxyntic cells) cells of the *gastric glands that secrete hydrochloric acid in the fundic region of the stomach.... parietal cells

Phalangeal Cells

rows of supporting cells between the sensory hair cells of the organ of Corti (see cochlea).... phalangeal cells

Prickle Cells

cells with cytoplasmic processes that form intercellular bridges. The germinative layer of the *epidermis is sometimes called the prickle cell layer.... prickle cells

Pyramidal Cell

a type of neuron found in the *cerebral cortex, with a pyramid-shaped cell body, a branched dendrite extending from the apex towards the brain surface, several dendrites extending horizontally from the base, and an axon running in the white matter of the hemisphere.... pyramidal cell

Reed–sternberg Cell

a large binucleate cell that is characteristic of *Hodgkin’s disease. [D. Reed Mendenhall (1874–1964), US pathologist; C. Sternberg (1872–1935), Austrian pathologist]... reed–sternberg cell

Regulatory T Cell

(Treg cell) a type of T *lymphocyte that suppresses immune responses.... regulatory t cell

Resting Cell

a cell that is not undergoing division. See interphase.... resting cell

Schwann Cells

the cells that lay down the *myelin sheath around the axon of a medullated nerve fibre. Each cell is responsible for one length of axon, around which it twists as it grows, so that concentric layers of membrane envelop the axon. The gap between adjacent Schwann cells forms a *node of Ranvier. [T. Schwann (1810–82), German anatomist and physiologist]... schwann cells

Sertoli Cells

cells found in the walls of the seminiferous tubules of the *testis. Compared with the germ cells they appear large and pale. They anchor and probably nourish the developing germ cells, especially the *spermatids, which become partly embedded within them. A Sertoli-cell tumour is a rare testicular tumour causing *feminization. [E. Sertoli (1842–1910), Italian histologist]... sertoli cells

Sickle-cell Nephropathy

progressive renal disease developing in 5–8% of patients with *sickle-cell disease. Infarcts in the cortex can occur with sickle-cell crises and present with pain and haematuria. Acute or more insidious damage to the medulla will lead to a urinary concentrating defect and later to papillary necrosis and/or fibrosis. Occlusion of vessels within the glomerular capillary tuft leads to a secondary form of *focal segmental glomerulosclerosis and can present with the *nephrotic syndrome.... sickle-cell nephropathy

Small-cell Lung Cancer

(SCLC) a type of bronchial carcinoma characterized by small cells (or oat cells), small round or oval cells with darkly staining nuclei and scanty indistinct cytoplasm. Small-cell carcinoma is usually related to smoking and accounts for about one-quarter of bronchial carcinomas; it carries a poor prognosis due to early distant spread, typically to bones, liver, and brain. Treatment is primarily with chemotherapy and radiotherapy and paraneoplastic symptoms (see paraneoplastic syndrome) from *ectopic hormone production are common. Compare non-small-cell lung cancer.... small-cell lung cancer

Sternberg–reed Cell

see Reed–Sternberg cell.... sternberg–reed cell

Suppressor T Cell

a type of T *lymphocyte that prevents an immune response by B cells or other T cells to an antigen.... suppressor t cell

Transitional Cell Carcinoma

a form of cancer that affects the urothelium, which lines the urinary collecting system of the kidney, ureters, bladder, and the proximal part of the urethra. It is the most common type of bladder cancer.... transitional cell carcinoma

Sickle-cell Disease

(drepanocytosis) a hereditary blood disease that mainly affects people of African ancestry but also occurs in the Mediterranean region and reaches high frequencies in parts of Saudi Arabia and India. It occurs when the sickle-cell gene has been inherited from both parents and is characterized by the production of an abnormal type of *haemoglobin – sickle-cell haemoglobin (Hbs) – which precipitates in the red cells when the blood is deprived of oxygen, forming crystals that distort the cells into the characteristic sickle shape: this process is known as sickling. An excess of sickle cells in the circulation results in blockage of small blood vessels, producing episodes of severe pain (a sickle-cell crisis). Sickle cells are rapidly removed from the circulation, leading to anaemia and jaundice. There is no satisfactory treatment; the highest mortality is in childhood but some patients may live to an age of 60–70 years.

The carrier condition (sickle-cell trait) occurs when the defective gene is inherited from only one parent. It generally causes no symptoms but confers some protection from malaria, which accounts for the high frequency of the gene in malarious areas. If a general anaesthetic is to be given to a patient with this condition, the anaesthetist should be alerted.... sickle-cell disease

Treg Cell

see regulatory T cell.... treg cell

Umbilical Cord Blood Banked Stem Cells

haemopoietic *stem cells collected from umbilical cord blood donated at birth, which can be stored indefinitely and used if a sibling or any other blood-compatible baby develops an illness (such as leukaemia) that could only be treated by cord-blood stem-cell transplantation. This facility is now available in the UK and the USA.... umbilical cord blood banked stem cells



Recent Searches