cell (sel)
Cell
cell
cell(s),
Patient discussion about Parafollicular cells.
1. any of the protoplasmic masses making up organized tissue, consisting of a nucleus surrounded by cytoplasm enclosed in a cell or plasma membrane. It is the fundamental, structural, and functional unit of living organisms. In some of the lower forms of life, such as bacteria, a morphological nucleus is absent, although nucleoproteins (and genes) are present.
2. a small, more or less closed space.
accessory cells macrophages involved in the processing and presentation of antigens, making them more immunogenic.
acid cells parietal c's.
acinar cell , acinic cell, acinous cell any of the cells lining an acinus, especially the zymogen-secreting cells of the pancreatic acini.
adventitial cell pericyte.
air cell
1. any minute bodily chamber filled with air, such as an alveolus of the lung.
2. a cavity containing air and surrounded by a bodily structure, usually one of the bones of the head, such as the ethmoid or mastoid.
alpha cell
1. a type of cell found in the periphery of the islets of Langerhans that secretes glucagon.
2. acidophil (2).
alveolar cell pneumonocyte; any cell of the walls of the pulmonary alveoli; often restricted to the cells of the alveolar epithelium (squamous alveolar cells and great alveolar cells) and alveolar phagocytes.
Alzheimer cells
1. giant astrocytes with large prominent nuclei found in the brain in hepatolenticular degeneration and hepatic coma.
2. degenerated astrocytes.
amacrine cell any of five types of retinal neurons that seem to lack large axons, having only processes that resemble dendrites.
ameboid cell a cell that shows ameboid movement.
Anichkov's cell a plump modified histiocyte in the inflammatory lesions of the heart (Aschoff bodies) characteristic of rheumatic fever.
APUD cells [a mine p recursor u ptake and d ecarboxylation] a group of cells that manufacture polypeptides and biogenic amines serving as hormones or neurotransmitters. The polypeptide production is linked to the uptake of a precursor amino acid and its decarboxylation to an amine.
argentaffin cells enterochromaffin cells that reduce ammoniacal silver solutions without additional treatment with a reducing agent; the reducing substance is serotonin.
Arias-Stella cells columnar cells in the endometrial epithelium which have a hyperchromatic enlarged nucleus and which appear to be associated with chorionic tissue in an intrauterine or extrauterine site.
Askanazy cells large eosinophilic cells found in the thyroid gland in autoimmune thyroiditis and Hürthle cell tumors.
automatic cell pacemaker c.
B cells B lymphocytes.
band cell a late metamyelocyte in which the nucleus is in the form of a curved or coiled band.
basal cell an early keratinocyte, present in the stratum basale of the epidermis.
basal granular cells APUD cells located at the base of the epithelium at many places in the gastrointestinal tract.
basket cell a neuron of the cerebral cortex whose fibers form a basket-like nest in which a Purkinje cell rests.
beaker cell goblet c.
beta cell
1. a type of basophilic cell that makes up most of the bulk of the islets of Langerhans and secretes insulin.
2. basophil (3).
Betz cells large pyramidal ganglion cells forming a layer of the gray matter of the brain.
bipolar cell a neuron with two processes.
blast cell
1. blast (1).
2. the least differentiated blood cell without commitment as to its particular series; it precedes a stem cell.
bone cell osteocyte.
bristle cells the hair cells associated with the auditory and cochlear nerves.
burr cell schistocyte.
cartilage cell chondrocyte.
CD4 cells a major classification of T lymphocytes, referring to those that carry CD4 antigens; most are helper cells.
CD8 cells a major classification of T lymphocytes, referring to those that carry the CD8 antigen, including cytotoxic T lymphocytes and suppressor cells.
chief cells
1. columnar or cuboidal epithelial cells that line the lower portions of the gastric glands and secrete pepsin.
2. pinealocytes.
3. the most abundant parenchymal cells of the parathyroid, being polygonal epithelial cells rich in glycogen, having granular cytoplasm and vesicular nuclei, and arranged in plates or cords; cf. oxyphil c's.
4. the principal chromaffin cells of the paraganglia, each of which is surrounded by supporting cells.
5. chromophobe c's.
chromaffin cells cells staining readily with chromium salts, especially those of the adrenal medulla and similar cells occurring in widespread accumulations throughout the body in various organs, whose cytoplasm shows fine brown granules when stained with potassium bichromate.
chromophobe cells faintly staining cells in the adenohypophysis; some are nongranular (either nonsecretory, immature presecretory, or degenerating cells), while others have extremely small granules; they are increased in chromophobe adenomas.
Claudius cells cuboidal cells, which along with Böttcher's cells form the floor of the external spiral sulcus, external to the organ of Corti.
columnar cell an elongated epithelial cell.
committed cell a lymphocyte which, after contact with antigen, is obligated to follow an individual course of development leading to antibody synthesis or immunological memory.
cell of Corti a hair cell in the organ of Corti.
cuboidal cell an epithelial cell whose transverse and vertical diameters are approximately equal.
daughter cell one formed by division of a mother cell.
decidual cells connective tissue cells of the uterine mucous membrane, enlarged and specialized during pregnancy.
Deiters cells the outer phalangeal cells of the organ of Corti.
delta cells cells in the pancreatic islets that secrete somatostatin.
dendritic cells cells with long cytoplasmic processes in the lymph nodes and germinal centers of the spleen; such processes, which extend along lymphoid cells, retain antigen molecules for extended periods of time.
dust cell alveolar macrophage.
effector cell any cell, such as an activated lymphocyte or plasma cell, which is instrumental in causing antigen disposal accomplished by either a cell-mediated or a humoral immunological response.
enamel cell ameloblast.
enterochromaffin cells chromaffin cells of the intestinal mucosa that stain with chromium salts and are impregnable with silver; they are sites of synthesis and storage of serotonin.
epithelial cells cells that cover the surface of the body and line its cavities.
epithelioid cells
1. large polyhedral cells of connective tissue origin.
2. highly phagocytic, modified macrophages, resembling epithelial cells, which are characteristic of granulomatous inflammation.
3. pinealocytes.
erythroid cells blood cells of the erythrocytic series.
ethmoid cells , ethmoidal cells, ethmoidal air cells ethmoidal sinuses; paranasal sinuses found in groups within the ethmoid bone and communicating with the ethmoidal infundibulum and bulla and the superior and highest meatuses; often subdivided into anterior, middle, and posterior.
eukaryotic cell a cell with a true nucleus; see eukaryote.
excitable cell a cell that can generate an action potential at its membrane in response to depolarization and may transmit an impulse along the membrane.
fat cell a connective tissue cell specialized for the synthesis and storage of fat; such cells are bloated with globules of triglycerides, the nucleus being displaced to one side and the cytoplasm seen as a thin line around the fat droplet.
fat-storing cell of liver lipid-accumulating, stellate cells located in the perisinusoidal space of the liver.
foam cells cells with a vacuolated appearance due to the presence of complex lipids; seen notably in xanthoma.
follicle cells , follicular cells cells located in the epithelium of follicles, such as those of the thyroid or ovarian follicles.
follicular center cell any of a series of B lymphocytes occurring normally in the germinal center and pathologically in the neoplastic nodules of follicular center cell lymphoma; they are believed to be intermediate stages in the development of lymphoblasts and plasma cells and are distinguished according to size (large or small) and the presence or absence of nuclear folds or clefts (cleaved or noncleaved).
G cells granular enterochromaffin cells in the mucosa of the pyloric part of the stomach, a source of gastrin.
ganglion cell a large nerve cell, especially one of those of the spinal ganglia.
Gaucher cell a large cell characteristic of Gaucher's disease, with eccentrically placed nuclei and fine wavy fibrils parallel to the long axis of the cell.
germ cells the cells of an organism whose function it is to reproduce its kind, i.e., oocytes and spermatozoa and their immature stages.
ghost cell
1. a keratinized denucleated cell with an unstained, shadowy center where the nucleus has been.
2. a degenerating or fragmented erythrocyte with no hemoglobin.
giant cell
1. any very large cell, such as the megakaryocyte of bone marrow.
2. any of the very large, multinucleate, modified macrophages, which may be formed by coalescence of epithelioid cells or by nuclear division without cytoplasmic division of monocytes, e.g., those characteristic of granulomatous inflammation and those that form around large foreign bodies.
glial cells neuroglial c's.
globoid cell an abnormal large histiocyte found in large numbers in intracranial tissues in Krabbe's disease.
glomus cell
1. any of the specific cells of the carotid body, which contain many dense-cored vesicles, occurring in clusters surrounded by other cells with no cytoplasmic granules.
2. any of the modified smooth muscle cells surrounding the arterial segment of a glomeriform arteriovenous anastomosis.
goblet cell a unicellular mucous gland found in the epithelium of various mucous membranes, especially that of the respiratory passages and intestines.
Golgi cells see under neuron.
granular cell one containing granules, such as a keratinocyte in the stratum granulosum of the epidermis, when it contains a dense collection of darkly staining granules.
granule cells
1. diminutive cells found in the granular layers of the cerebral and cerebellar cortices.
2. small nerve cells without axons, whose bodies are in the granular layer of the olfactory bulb.
granulosa cells cells surrounding the graafian follicle and forming the stratum granulosum and cumulus oophorus, after ovulation becoming lutein cells.
gustatory cells taste c's.
hair cells sensory epithelial cells with long hairlike processes (kinocilia or stereocilia) found in the organ of Corti and the vestibular labyrinth.
hairy cell one of the abnormal large leukocytes found in the blood in hairy cell leukemia, having numerous irregular cytoplasmic villi that give the cell a flagellated or hairy appearance.
heart-disease cells , heart-failure cells, heart-lesion cells macrophages containing granules of iron, found in the pulmonary alveoli and sputum in congestive heart failure.
HeLa cells cells of the first continuously cultured carcinoma strain, descended from a human cervical carcinoma.
helmet cell schistocyte.
helper cells , helper T cells differentiated T lymphocytes which cooperate with B lymphocytes in the synthesis of antibody to many antigens; they play an integral role in immunoregulation.
Hensen cells tall supporting cells constituting the outer border of the organ of Corti.
hepatic cells the polyhedral epithelial cells that constitute the substance of an acinus of the liver.
horizontal cell a retinal neuron, occurring in two types, each with one long neurite and several short ones.
Hürthle cells Askanazy c's.
interdental cells cells found in the spiral limbus between the dens acustici, which secrete the tectorial membrane of the cochlear duct.
interstitial cells
1. Leydig c's (1).
2. large epithelioid cells in the ovarian stroma, believed to have a secretory function, derived from the theca interna of atretic ovarian follicles.
3. cells found in the perivascular areas and between the cords of pinealocytes in the pineal body.
interstitial cells of Cajal pleomorphic cells having an oval nucleus and long, branching cytoplasmic processes that interlace with processes of adjacent cells, occurring in the gastrointestinal tract and the esophagus; thought to act as pacemakers.
islet cells the alpha and beta cells of the islets of Langerhans.
juxtaglomerular cells specialized cells containing secretory granules, located in the tunica media of the afferent glomerular arterioles, thought to stimulate aldosterone secretion and to play a role in renal autoregulation. These cells secrete the enzyme renin.
K cells
1. killer cells; cells mediating antibody-dependent cell-mediated cytotoxicity; they are small lymphocytes without T or B cell surface markers, having cytotoxic activity against target cells coated with specific IgG antibody.
2. cells in the duodenal and jejunal mucosa that synthesize gastric inhibitory polypeptide.
killer cells
1. K c's (1).
Kupffer cells large, stellate or pyramidal, intensely phagocytic cells lining the walls of the hepatic sinusoids and forming part of the reticuloendothelial system. 
)
Kupffer cells lining a hepatic sinusoid.
lacunar cell a variant of the Reed-Sternberg cell, primarily associated with the nodular sclerosis type of Hodgkin's disease.
LAK cells lymphokine-activated killer c's.
Langerhans cells stellate dendritic cells, derived from precursors in the bone marrow, containing characteristic inclusions (Birbeck granules) in the cytoplasm and found principally in the epidermis. They are believed to be antigen-presenting cells involved in cell-mediated immune reactions in the skin.
large cleaved cell see follicular center c.
large noncleaved cell , large uncleaved cell see follicular center c.
LE cell a neutrophil or macrophage that has phagocytized the denatured nuclear material of an injured cell (hematoxylin body); a characteristic of lupus erythematosus, but also found in analogous connective tissue disorders.
Leydig cells
1. clusters of epithelioid cells constituting the endocrine tissue of the testis, which elaborate androgens, chiefly testosterone.
2. mucous cells that do not pour their secretion out over the epithelial surface.
littoral cells flattened cells lining the walls of lymph or blood sinuses.
luteal cells , lutein cells the plump, pale-staining, polyhedral cells of the corpus luteum.
lymph cell lymphocyte.
lymphokine-activated killer cells killer cells activated by interleukin-2 and having specificity for tumors refractory to NK cells.
lymphoid cells lymphocytes and plasma cells; cells of the immune system that react specifically with antigen and elaborate specific cell products.
mast cell a connective tissue cell capable of elaborating basophilic, metachromatic cytoplasmic granules that contain histamine, heparin, hyaluronic acid, slow-reacting substance of anaphylaxis, and, in some species, serotonin.
mastoid cells air cells of various sizes and shapes in the mastoid process of the temporal bone.
Merkel cell a specialized cell at or near the epithelial–dermal junction and believed to act as a touch receptor by association with the flat, disklike ending of a nerve fiber (tactile meniscus).
Mexican hat cell target c. (1).
microglial cell a cell of the microglia.
mother cell one that divides to form new, or daughter, cells.
mucous cells cells which secrete mucus or mucin.
muscle cell see under fiber.
myoid cells cells in the seminiferous tubules which are presumed to be contractile and to be responsible for the rhythmic shallow contractions of the tubules.
natural killer cells NK c's.
nerve cell neuron.
neuroendocrine cells the specialized neurons that secrete neurohormones.
neuroglia cells , neuroglial cells the branching, non-neural cells of the neuroglia; they are of three types: astroglia, oligodendroglia (collectively termed macroglia), and microglia.
neurosecretory cell any cell with neuron-like properties that secretes a biologically active substance acting on another structure, often at a distant site.
nevus cell a small oval or cuboidal cell with a deeply staining nucleus and scanty pale cytoplasm, sometimes containing melanin granules, possibly derived from Schwann cells or embryonal nevoblasts; they are clustered in rounded masses (theques ) in the epidermis, and reach the dermis by a kind of centripetal extrusion.
Niemann-Pick cells Pick c's.
NK cells natural killer cells; cells capable of mediating cytotoxic reactions without themselves being specifically sensitized against the target.
null cells lymphocytes that lack the surface antigens characteristic of B and T lymphocytes; seen in active systemic lupus erythematosus and other disease states.
nurse cells , nursing cells Sertoli c's.
olfactory cells a set of specialized cells of the mucous membranes of the nose, which are receptors of smell.
osteoprogenitor cells relatively undifferentiated cells found on or near all of the free surfaces of bone, which, under certain circumstances, undergo division and transform into osteoblasts or coalesce to give rise to osteoclasts.
oxyntic cells parietal c's.
oxyphil cells , oxyphilic cells
1. acidophilic cells found, along with the more numerous chief cells, in the parathyroid glands.
2. Askanazy c's.
P cells poorly staining, pale, small cells almost devoid of myofibrils, mitochondria, or other organelles; they are clustered in the sinoatrial node, where they are thought to be the center of impulse generation, and in the atrioventricular node.
pacemaker cell a myocardial cell displaying automaticity.
packed red blood cells whole blood from which plasma has been removed; used therapeutically in blood transfusions.
Paget cell , pagetoid cell a large, irregularly shaped, pale anaplastic tumor cell found in the epidermis in Paget's disease of the nipple and in extramammary Paget's disease.
Paneth cells narrow, pyramidal, or columnar epithelial cells with a round or oval nucleus close to the base of the cell, occurring in the fundus of the crypts of Lieberkühn; they contain large secretory granules that may contain peptidase.
parafollicular cells ovoid epithelial cells located in the thyroid follicles; they secrete calcitonin.
parietal cells large spheroidal or pyramidal cells that are the source of gastric hydrochloric acid and are the site of intrinsic factor production.
peptic cells chief c's (1).
peritubular contractile cells myoid c's.
pheochrome cells chromaffin c's.
Pick cells round, oval, or polyhedral cells with foamy, lipid-containing cytoplasm, found in the bone marrow and spleen in Niemann-Pick disease.
pigment cell any cell containing pigment granules.
pillar cells elongated supporting cells in a double row (inner and outer pillar c's) in the organ of Corti, arranged to form the inner tunnel. 
)
Pillar cells forming the inner tunnel in the organ of Corti in the inner ear.
plasma cell spherical or ellipsoidal cells with a single nucleus containing chromatin, an area of perinuclear clearing, and generally abundant, sometimes vacuolated, cytoplasm; they are involved in the synthesis, storage, and release of antibody.
polychromatic cells , polychromatophil cells immature erythrocytes staining with both acid and basic stains in a diffuse mixture of blue-gray and pink.
pre-B cells lymphoid cells that are immature and contain cytoplasmic IgM; they develop into B lymphocytes.
pre-T cell a T lymphocyte precursor before undergoing induction of the maturation process in the thymus; it lacks the characteristics of a mature T lymphocyte.
prickle cell a cell with delicate radiating processes connecting with similar cells, being a dividing keratinocyte of the stratum spinosum (prickle cell layer) of the epidermis.
primordial germ cell the earliest recognizable precursor in the embryo of a germ cell; these originate extragonadally but migrate early in embryonic development to the gonads.
prokaryotic cell a cell without a true nucleus; see prokaryote.
pulmonary epithelial cells extremely thin nonphagocytic squamous cells with flattened nuclei, constituting the outer layer of the alveolar wall in the lungs.
Purkinje's cells
1. large branching neurons in the middle layer of the cerebellar cortex.
2. large, clear, tightly packed, impulse-conducting cells of the cardiac Purkinje fibers.
red cell , red blood cell erythrocyte.
red blood cells official terminology for packed red blood c's.
Reed cells , Reed-Sternberg cells the giant histiocytic cells, typically multinucleate, which are the common histologic characteristic of Hodgkin's disease.
reticular cells the cells forming the reticular fibers of connective tissue; those forming the framework of lymph nodes, bone marrow, and spleen form part of the reticuloendothelial system and may differentiate into macrophages.
reticuloendothelial cell see under system.
Rieder cell see under lymphocyte.
Schwann cell any of the large nucleated cells whose cell membrane spirally enwraps the axons of myelinated peripheral neurons supplying the myelin sheath between two nodes of Ranvier.
segmented cell a mature granulocyte in which the nucleus is divided into definite lobes joined by a filamentous connection.
Sertoli cells cells in the seminiferous tubules to which the spermatids become attached and which support, protect, and apparently nourish the spermatids until they develop into mature spermatozoa.
sickle cell a crescentic or sickle-shaped erythrocyte, characteristic of sickle cell anemia.
small cleaved cell see follicular center c.
small noncleaved cell , small uncleaved cell see follicular center c.
somatic cells the cells of the somatoplasm; undifferentiated body cells.
somatostatin cells endocrine cells of the oxyntic and pyloric glands that secrete somatostatin.
sperm cell spermatozoon.
spur cell acanthocyte.
squamous cell a flat, scalelike type of epithelial cell.
stab cell , staff cell band c.
stellate cell any star-shaped cell, as a Kupffer cell or astrocyte, having many filaments extending in all directions.
stem cell a generalized mother cell that has pluripotency (descendants may specialize in different directions), such as an undifferentiated mesenchymal cell that is a progenitor of both red and white blood cells.
suppressor cells lymphoid cells, especially T lymphocytes, that inhibit humoral and cell-mediated immune responses. They play an integral role in immunoregulation, and are believed to be operative in various autoimmune and other immunological disease states.
synovial cells fibroblasts lying between the cartilaginous fibers in the synovial membrane of a joint.
T cells T lymphocytes.
target cell
1. an abnormally thin erythrocyte that when stained shows a dark center surrounded by a pale unstained ring and a peripheral ring of hemoglobin; seen in certain anemias, thalassemias, hemoglobinopathies, obstructive jaundice, and the postsplenectomy state.
2. any cell selectively affected by a particular agent, such as a hormone or drug.
taste cells cells in the taste buds that have gustatory receptors.
tendon cells flattened cells of connective tissue occurring in rows between the primary bundles of the tendons.
theca cells , theca-lutein cells lutein cells derived from the theca interna of the graafian follicle.
transitional cells
1. cells in the process of changing from one type to another.
2. in the sinoatrial and atrioventricular nodes, small, slow-conducting, heterogeneous cells interposed between the P cells and Purkinje cells.
visual cells the neuroepithelial elements of the retina.
white cell , white blood cell leukocyte.
cell (s l)n. 1. The smallest structural unit of an organism that is capable of independent functioning, consisting of one or more nuclei, cytoplasm, and various organelles, all surrounded by a semipermeable cell membrane. 2. A small enclosed cavity or space. |  human cell sectioned for electron microscopy |
Cell
The smallest living units of the body which group together to form tissues and help the body perform specific functions.
cell
Etymology: L, cella, storeroom
the fundamental unit of all living tissue. Eukaryotic cells consist of a nucleus, cytoplasm, and organelles surrounded by a plasma membrane. Within the nucleus are the nucleolus (containing ribonucleic acid) and the chromatin (containing protein and deoxyribonucleic acid), which form chromosomes, wherein are located the determinants of inherited characteristics. Organelles within the cytoplasm include the endoplasmic reticulum, ribosomes, Golgi apparatus, mitochondria, lysosomes, and centrosome. Prokaryotic cells are much smaller and simpler than eukaryocytic cells, even lacking a nucleus. The specialized nature of body tissue reflects the specialized structure and function of its constituent cells. See also cell theory. cellular, adj.
cell(s),
n the basic unit of vital tissue. One of a large variety of microscopic protoplasmic masses that make up organized tissues. Each cell has a cell membrane, protoplasm, nucleus, and a variety of inclusion bodies. Each type of cell is a living unit with its own metabolic requirements, functions, permeability, ability to differentiate into other cells, reproducibility, and life expectancy.
cell, beta,
n any cell that produces insulin in the islets of Langerhans region of the pancreas.
cell, bone-forming,
n.pl See osteoblast.
cell, central, of the dental papillae,
n the inner cells of the dental papilla within the concavity of the enamel organ that are the primordium of the pulp.
cell
1. the basic structural unit of living organisms.
2. a small more or less enclosed space.
All living cells arise from other cells, either by division of one cell to make two, as in mitosis and meiosis, or by fusion of two cells to make one, as in the union of the sperm and ovum to make the zygote in sexual reproduction.
All cells are bounded by a structure called the cell membrane or plasma membrane, which is a lipid bilayer composed of two layers of phospholipids. Each layer is one molecule thick with the charged, hydrophilic end of the lipid molecules on the surface of the membrane and the uncharged hydrophobic fatty acid tails in the interior of the membrane.
Cells are divided into two classes, eukaryotic cells and prokaryotic cells:
Eukaryotic cells have a true nucleus, which contains the genetic material, composed of the chromosomes, each of which is a long linear deoxyribonucleic acid (DNA) molecule associated with protein. The nucleus is bounded by a nuclear membrane, which is composed of two lipid bilayer membranes.
Prokaryotic cells, the bacteria, have no nucleus, and their genetic material, consisting of a single circular naked DNA molecule, is not separated from the rest of the cell by a nuclear membrane.
Eukaryotic cells are larger and more complex than prokaryotic cells. They also have membrane-bounded structures, such as mitochondria, chloroplasts, Golgi apparatus, endoplasmic reticulum and lysosomes, that prokaryotic cells lack.
The contents of a cell are referred to collectively as the protoplasm. In eukaryotic cells the contents of the nucleus are referred to as nucleoplasm and the rest of the protoplasm as the cytoplasm.
The lipid bilayer of eukaryotic cells is impermeable to many substances, such as ions, sugars and amino acids; however, membrane proteins selectively move specific substances through the cell membrane by active or passive transport. Water, gases such as oxygen and carbon dioxide, and nonpolar compounds pass through the cell membrane by diffusion. Materials can also be engulfed and taken into the cell enclosed in a portion of the cell membrane. This is called phagocytosis when solids are ingested and pinocytosis when liquids are ingested. The reverse process is called exocytosis. All of these processes permit the cell to maintain an internal environment different from its exterior. See also body fluids.
The cells of the body differentiate during development into many specialized types with specific tasks to perform. Cells are organized into tissues and tissues into organs. Embedded in the cell membrane are a wide range of molecules that vary with the cell type and are typically composed of proteins or glycoproteins that have a cytoplasmic transmembrane and external domains. These molecules serve as cell receptors and are involved in signal transduction for a wide range of ligands, including hormones, cytokines and incidentally serve as receptors for viruses and drugs.
See also betz cells, gaucher's cells, golgi's cells, hela cells, hürthle cell, kupffer's cells, merkel cell, mesangial cell, neuroendocrine cell.
)
Structure of the cell as seen by light microscopy. By permission from Guyton R, Hall JE, Textbook of Medical Physiology, Saunders, 2000
accessory c's
macrophages involved in the processing and presentation of antigens making them immunogenic.
acinar cell, acinous cell
any of the cells lining an acinus, especially applied to the zymogen-secreting cells of the pancreatic acini.
adherent cell
one that adheres to the glass or plastic container in cell cultures, to form the monolayer. See also cell culture.
alpha c's
1. cells in the islets of Langerhans that secrete glucagon.
2. acidophilic cells of the anterior pituitary.
APUD c's
see apud cells.
argentaffin c's
enterochromaffin cells containing cytoplasmic granules capable of reducing silver compounds, located throughout the gastrointestinal tract, chiefly in the basilar portions of the gastric glands and the crypts of Lieberkühn. They secrete serotonin.
band cell
an immature neutrophil in which the nucleus is not lobulated but is in the form of a continuous band, horseshoe shaped, twisted or coiled. Called also band-form granulocyte and stab cell.
basal cell
an early keratinocyte, present in the basal layer of the epidermis.
basket c's
cells in the cerebellar cortex whose axons carry basket-like groups of fibrils which enclose the cell body of each Purkinje cell.
beta c's
1. basophilic cells in the pancreas that secrete insulin and make up most of the bulk of the islets of Langerhans; they contain granules that are soluble in alcohol.
2. basophilic cells of the anterior pituitary.
blood cell
one of the formed elements of the blood. See also blood.
cell body
the nucleus of the cell and the adjacent cytoplasm in cells which have processes, e g. neurons which consist of a cell body, an axon and dendrites.
bone cell
a nucleated cell in the lacunae of bone. Called also osteocyte.
cartilage cell
chondrocyte.
chromaffin c's
cells whose cytoplasm shows fine brown granules when stained with potassium bichromate, occurring in the adrenal medulla and in scattered groups in various organs and throughout the body.
cleavage cell
any of the cells derived from the fertilized ovum by mitosis; a blastomere.
cell count
cell culture
see cell culture.
cell cycle
see cell cycle.
daughter cell
a cell formed by division of a mother cell.
cell dehydration
fluid loss from cells due to elevation of the osmotic pressure of blood and tissue fluid; a potent stimulus to thirst.
dendritic cell
macrophage-like cells with long, filamentous processes located in the cortex of lymph nodes and the skin. Important in antigen trapping, processing and presentation. See also langerhans' cell.
cell differentiation
the process whereby cells become specialized usually with concurrent loss of reproductive capacity.
embryonic stem cell
a stem cell of fetal origin. See stem cell (below).
epithelioid cell
enlarged macrophages with enlarged lysosomes and much endoplasmic reticulum. May fuse to form multinucleated giant cell (below).
epsilon cell
one of the groups of acidophilic cells in the adenohypophysis. Contains granules that stain with azocarmine dye.
foam cell
a cell with a vacuolated appearance due to the presence of complex lipoids; seen in xanthoma.
cell fusion
see syncytial giant cell.
ganglion cell
a large nerve cell, especially one of those of the spinal ganglia.
germ cell
see germ cell.
giant cell
a very large, multinucleate cell; applied to megakaryocytes of bone marrow, to giant cells formed by coalescence and fusion of macrophages occurring in infectious granulomas and about foreign bodies, and to certain cancer cells.
glial c's
neuroglial cells.
goblet cell
a unicellular mucous gland found in the epithelium of various mucous membranes, especially that of the respiratory passages and intestines.
granular cell
one containing granules, such as a keratinocyte in the stratum granulosum of the epidermis, when it contains a dense collection of darkly staining granules.
gustatory cell
see taste bud.
heart failure c's, heart lesion c's
iron-containing, rust-colored macrophages found in the pulmonary alveoli in congestive heart failure.
helmet cell
schistocyte.
helper cell
a subset of T lymphocytes which cooperate with B and other T lymphocytes for the synthesis of antibodies to many antigens; they play an integral role in immunoregulation.
hybrid cell
a mononucleate cell produced from a binucleate heterokaryon after the latter undergoes mitosis. Such cells are initially unstable, tending to lose randomly some of the double complement of chromosomes. Used for mapping genes to particular chromosomes. See also heterokaryon, hybridoma.
immunologically competent cell
see immunocyte.
interstitial c's
the cells of the connective tissue of the ovary or of the testis (Leydig's cells) which furnish the internal secretion of those structures, i.e. testosterone.
islet c's
cells composing the islets of Langerhans in the pancreas. See alpha cells, beta cells (above).
juxtaglomerular c's
specialized cells, containing secretory granules, located in the tunica media of the afferent glomerular arterioles. They cause aldosterone production by secreting the enzyme renin and play a role in the regulation of blood pressure and fluid balance.
K c's, killer c's
T lymphocytes or null lymphocytes that have cytotoxic activity against target cells coated with specific IgG antibody.
lacis cell
accumulation of cells between the arterioles at the glomerular hilus. Called also granular cell.
lacunar cell
precursor of the malignant interdigitating reticular cell in Hodgkin-like lymphoma in humans.
LE cell
a mature neutrophilic polymorphonuclear leukocyte characteristic of lupus erythematosus. See also lupus erythematosus (le) cell.
Leydig's c's
interstitial cells of the testis, which secrete testosterone.
cell line
see cell culture.
lutein c's
the plump, pale-staining, polyhedral cells of the corpus luteum.
lymph cell
lymphocyte.
lymphoid c's
lymphocytes and plasma cells.
mast cell
a connective tissue cell that has basophilic, metachromatic cytoplasmic granules that contain histamine, heparin, hyaluronic acid, slow-reacting substance of anaphylaxis (SRS-A), and, in some species, serotonin. Have Fc receptors specific for IgE in the cell membrane.
cell-mediated immune reaction
see cellular immunity.
cell migration
movement of cells from their place of origin to other tissues; one of the fundamental processes of development.
microglial cell
see microglia. See also neuroglia cells (below).
milk cell count
see milk cell counts.
mother cell
a cell that divides to form new, or daughter, cells.
Mott cell
a plasma cell with large, clear cytoplasmic pockets.
natural killer c's, NK c's
cells capable of mediating cytotoxic reactions without themselves being specifically sensitized against the target.
nerve cell
any cell of the nervous system; a neuron.
cell nests
see isogenous groups.
neuroglia c's, neuroglial c's
see neuroglia.
null c's
lymphocyte-like cells that lack specific antigen receptors and other surface markers characteristic of B and T lymphocytes; they include K and NK cells; their numbers are elevated in active systemic lupus erythematosus and other disease states.
olfactory c's
a set of specialized cells of the mucous membrane of the nose; the receptors for smell.
parafollicular c's
see c cell.
Pick's c's
round, oval or polyhedral cells with foamy, lipid-containing cytoplasm found in the bone marrow and spleen in Niemann-Pick disease.
plasma cell
a spherical or ellipsoidal cell with a single, eccentrically placed nucleus containing dense masses of chromatin in a wheel-spoke arrangement, an area of perinuclear clearing which contains the Golgi apparatus, and generally abundant cytoplasm. Plasma cells are produced by cell division of B lymphocytes following antigen stimulation and are involved in the synthesis and release of antibody. Called also plasmacyte and plasmocyte.
prickle cell
a dividing keratinocyte of the prickle-cell layer of the epidermis, with delicate radiating process connecting with other similar cells.
prokaryotic cell
see prokaryote.
Purkinje's c's
large branching cells of the middle layer of the cerebellar cortex.
red cell, red blood cell
erythrocyte.
Reed-Sternberg c's
giant histiocytic cells, typically multinucleate, which are the common histological characteristic of Hodgkin's disease in humans.
reticular c's
the cells forming the reticular fibers of connective tissue; those forming the framework of lymph nodes, bone marrow and spleen. They are weakly phagocytic, stromal in origin and are distinct from the monocyte-macrophage system.
reticuloendothelial cell
a cell of the reticuloendothelial system.
Schwann cell
any of the large nucleated cells whose cell membrane spirally enwraps the axons of myelinated peripheral neurons supplying the myelin sheath between two nodes of Ranvier.
Sertoli c's
elongated cells in the tubules of the testes to which the spermatids become attached; they provide support, protection and, apparently, nutrition until the spermatids are transformed into mature spermatozoa.
sickle cell
a crescentic or sickle-shaped erythrocyte seen in some humans and deer. The abnormal shape caused by the presence of varying proportions of hemoglobin S.
signet-ring cell
a cell in which the nucleus has been pressed to one side by an accumulation of intracytoplasmic mucin.
somatic c's
the cells of the body other than the germ cells.
cell sorting
see fluorescence-activated cell sorter.
cell specialization
conversion of a simple cell type into a specialized cell type capable of a special function, e.g. a secretory cell; a major part of the growth of an embryo and the differentiation of basic mesenchymal tissue into specialized organs.
spindle cell
spindle shaped cells of the dermis or subcutis; principal component of spindle cell tumors.
spur cell
spiculed mature erythrocyte.
squamous c's
flat, scalelike epithelial cells.
stab cell
see band cell (above).
stellate cell
any star-shaped cell, as a Kupffer cell or astrocyte, having many filaments extending in all directions.
stem cell
1. any precursor cell.
2. a primitive hematopoietic cell that is capable of self-replicating or differentiating into precursor cells of erythrocytes or any of the leukocytes.
stipple cell
an erythrocyte containing granules that take a basic or bluish stain with Wright's stain.
suppressor c's
a not well defined subset of T lymphocytes that are reported to inhibit antibody and cell-mediated immune responses. They may play a role in immunoregulation, and are believed to be abnormal in various autoimmune and other immunological disease states. See also T lymphocytes.
target cell
1. an abnormally thin erythrocyte showing, when stained, a dark center and a peripheral ring of hemoglobin, separated by a pale, unstained zone containing less hemoglobin; seen in various anemias and other disorders. Called also codocyte.
2. any cell selectively affected by a particular agent, such as a hormone or drug.
3. cell containing nonself antigens in its cell membranes that is a target for nonimmune and immune cytolysis, e.g. virus-infected or tumor cell.
taste c's
cells in the taste buds associated with the nerves of taste.
cell therapy
see glandular therapy.
totipotential cell
an embryonic cell that is capable of developing into any type of body cell.
Türk's cell
a lymphocyte with increased basophilia.
visual c's
the neuroepithelial elements of the retina.
white cell, white blood cell
leukocyte.
cell
1. In biology, the basic, structural and functional units from which living organisms and tissues are built. A cell consists of a nucleus surrounded by all the cellular contents (cytoplasm) including various organelles (mitochondria, Golgi apparatus, lysosomes, ribosomes, etc.) and inclusions (glycogen, melanin, triglycerides, etc.) suspended in intracellular fluid (water, proteins, carbohydrates, lipids, inorganic and organic substances) all enclosed in a plasma membrane. There are many types of cells (blood cells, connective tissue cells, epithelial cells, muscle cells, nerve cells, secretory cells, etc.). Living cells are capable of reproduction (for body growth, wound healing, etc.) by mitotic activity.
2. In optics, a rim in a trial frame or in an optical instrument into which a lens can be placed.
A cell See M cell.
acinar cell A type of cell found within the body of the lacrimal gland. This cell lines the lumens of glands in a lobular pattern and produces a serous secretion.
amacrine cell Retinal cell located in the inner nuclear layer connecting ganglion cells with bipolar cells. Some have an ascending axon synapsing with receptors.
B cell See P cell.
basal cell See corneal epithelium.
binocular cell A cell in the visual cortex that responds to stimulation from both eyes. It may, however, show an ocular dominance for either eye. It responds more strongly when corresponding regions of each eye are stimulated by targets of similar size and orientation. See cortical column; hypercolumn.
bipolar cell Retinal cell located in the inner nuclear layer connecting the photoreceptors with amacrine and ganglion cells.
C cell A retinal ganglion cell with slow axonal conduction which sends information to the superior colliculus and to the centre involved in the control of pupillary diameter, rather than to the lateral geniculate body. There are very few such cells. Syn. Pγ cell; W cell (thus called in the cat).
Cajal's cell See astrocytes.
clump cell Large, pigmented round cells found in the pupillary zone of the iris stroma. They are considered to be macrophages containing mainly melanin granules. The number of these cells increases with age.
colour-opponent cell's Cells which respond by increasing response to light of some wavelengths and decreasing their response to others (usually complementary). If the light stimulus contains both sets of wavelengths the two responses tend to cancel each other. Two types of cells have been identified: red-green cells and blue-yellow cells. These cells are found mainly in the lateral geniculate bodies but also among retinal ganglion cells, and they form the blobs in the visual cortex. The responses of these cells support Hering's theory of colour vision. Syn. opponent-process cell (although this term also includes a cell that increases its response to white light and decreases its response to dark). See blobs; Hering's of colour vision theory.
complex cell A cell in the visual cortex whose receptive field consists of a large responsive area, approximately rectangular in shape, surrounded by an inhibitory region. The stimulus, which is usually a slit or a straight line, gives an optimum response if appropriately orientated but falling anywhere within the excitatory area. These cells tend to respond optimally to the movement of a specifically orientated slit. Many complex cells also respond better when the optimally orientated slit is moved in one direction rather than in the opposite direction. In general, complex cells show non-linear spatial summation properties. See visual area; hypercomplex cell; simple cell; receptive field; summation.
cone cell Photoreceptor of the retina which connects with a bipolar cell and is involved in colour vision and high visual acuity and which functions in photopic vision. The outer segment of the cell is conical in shape, except in the fovea centralis where it is rod-like. In the outer segment (i.e. the part closest to the pigment epithelium) are contained hollow discs (or lamellae), the membranes of which are joined together and are also continuous with the boundary membrane of the cone cell. The visual pigments are contained in these discs. There are three types of cones, each containing a different pigment sensitive to a different part of the light spectrum. They are referred to as long-wave-sensitive (or L-cones), medium-wave-sensitive (or M-cones) and short-wave-sensitive (or S-cones). There are about six million cones in the retina, with the greatest concentration in the macular area (Fig. C4). See cone pedicle; Stiles-Crawford effect; ellipsoid; foveola; macula; visual pigment; duplicity theory; photopic vision.
fixed cell See corneal corpuscle.
ganglion cell 1. Retinal cell that connects the bipolars and other cells in the inner plexiform layer with the lateral geniculate body. The axons of the ganglion cells constitute the optic nerve fibres. There are many types of ganglion cells. The two major types are: the magno (M or parasol) ganglion cells which project mainly to the magnocellular layers of the lateral geniculate bodies; and the parvo (P) ganglion cells which project to the parvocellular layers of the lateral geniculate bodies. Two types of P ganglion cells are noted: P1, which are midget cells and have small dendritic fields and P2, which have large dendritic fields. M and P cells comprise about 10% and 82% of the ganglion cells respectively. 2. One of a collection of nerve cell bodies found in a ganglion. See C cell; M cell; P cell; melanopsin.
glial cell's Cells found throughout the nervous system. They provide support and nutrition for neurons, as well as being involved in the operation of the brain, especially the fluid surrounding the neurons and their synapses. They are also believed to be involved in the reuptake of neurotransmitters from within the synaptic cleft. There are three types of glial cells: astrocytes; microglia; oligodendroglia. Syn. glia; neuroglia.
goblet cell Cell of the conjunctival epithelium which secretes mucin. See glands of Henle; mucin; xerophthalmia.
horizontal cell Retinal cell located in the inner nuclear layer which connects several cones and rods together.
hypercomplex cell A cell in the visual cortex that receives inputs from several simple and complex cells and therefore has an even more elaborate receptive field than a complex cell. It is most effectively stimulated by a stimulus of a specific size and of a specific orientation and which is moved in a specific direction. See complex cell; simple cell.
Langerhans' cell's Dendritic cells located mainly in the epidermis, mucous membranes and lymph nodes. They have surface receptors for immunoglobulin (Fc), complement (C3) and surface HLA-DR (Ia) antigen. Langerhans' cells are also found in the conjunctival epithelium and among the basal cells, mainly of the peripheral corneal epithelium. They have antigenic functions, stimulate T-lymphocytes, prostaglandin production and participate in cutaneous delayed hypersensitivity and corneal graft rejection. Extended wear of contact lenses tends to induce an increase of these cells. They are also found in histiocytic tumours.
M cell A retinal ganglion cell, mainly located in the periphery of the retina and which assists in movement perception. M cells tend to give transient responses to stimuli and to have non-linear spatial summation properties. This cell transmits information principally to the magno cells of the lateral geniculate bodies. Syn. A cell; Pαcell; Y cell (thus called in the cat).
magno cell See ganglion cell; lateral geniculate bodies.
midget cell See ganglion cell.
Mueller's cell Neuroglial cell in the retina with its nucleus in the inner nuclear layer and with fibres extending from the external to the internal limiting membrane. These cells support the neurons of the retina and possibly assist in their metabolism. Syn. Müller cell.
orientation-specific cell A cell that responds best to specifically orientated lines. This is the case for almost all cells in the visual cortex. Examples: complex cell; simple cell. See complex cell; simple cell; receptive field.
P cell A retinal ganglion cell, mainly located in the central region of the retina and which assists in high acuity and colour vision. P cells tend to give sustained responses to stimuli and to have linear spatial summation properties. This is the most common type of ganglion cells (about 82%). This cell transmits information principally to the parvo cells of the lateral geniculate bodies. Syn. B cell; Pβcell; X cell (thus called in the cat).
parasol cell See ganglion cell.
parvo cell See ganglion cell; lateral geniculate bodies.
rod cell Photoreceptor cell of the retina which connects with a bipolar cell. It contains rhodopsin and is involved in scotopic vision. The molecules of rhodopsin are contained in about 1000 hollow discs (double lamellae or membranes), which are isolated from each other and from the boundary membrane of the rod cell. These discs are found in the outer segment (i.e. the part closest to the pigment epithelium) of the cell. There are about 100 million rod cells throughout the retina; only a small area, the foveola, is free of rods (Fig. C4). See eccentricity; ellipsoid; foveola; rhodopsin; rod spherule; duplicity theory; scotopic vision.
Schwann cell A cell whose membrane spirals around the axon with layers of myelin in between each coil, as well as being a source of the myelin sheath. The cell provides insulation to the axon. It covers about one millimetre, so that hundreds may be needed to completely cover an axon. It also allows for an increase in the speed of the nervous impulse without an increase in axonal diameter. The gaps between the segments covered by the cells are called nodes of Ranvier. See action potential.
simple cell A cell in the visual cortex whose receptive field consists of an excitatory and an inhibitory area separated by a straight line, or by a long narrow strip of one response flanked on both sides by larger regions of the opposite response. Responses occur only to a straight line or a narrow strip orientated approximately parallel to the boundary/ies between the two areas. In general, simple cells show linear spatial summation properties. They are presumably the first cells where the nervous impulses are processed as they enter the visual cortex. See visual area; complex cell; receptive field.
squamous cell See corneal epithelium.
W cell See C cell.
wing cell See corneal epithelium.
X cell See P cell.
Y cell See M cell.
A cell See M cell.
acinar cell A type of cell found within the body of the lacrimal gland. This cell lines the lumens of glands in a lobular pattern and produces a serous secretion.
amacrine cell Retinal cell located in the inner nuclear layer connecting ganglion cells with bipolar cells. Some have an ascending axon synapsing with receptors.
B cell See P cell.
basal cell See corneal epithelium.
binocular cell A cell in the visual cortex that responds to stimulation from both eyes. It may, however, show an ocular dominance for either eye. It responds more strongly when corresponding regions of each eye are stimulated by targets of similar size and orientation. See cortical column; hypercolumn.
bipolar cell Retinal cell located in the inner nuclear layer connecting the photoreceptors with amacrine and ganglion cells.
C cell A retinal ganglion cell with slow axonal conduction which sends information to the superior colliculus and to the centre involved in the control of pupillary diameter, rather than to the lateral geniculate body. There are very few such cells. Syn. Pγ cell; W cell (thus called in the cat).
Cajal's cell See astrocytes.
clump cell Large, pigmented round cells found in the pupillary zone of the iris stroma. They are considered to be macrophages containing mainly melanin granules. The number of these cells increases with age.
colour-opponent cell's Cells which respond by increasing response to light of some wavelengths and decreasing their response to others (usually complementary). If the light stimulus contains both sets of wavelengths the two responses tend to cancel each other. Two types of cells have been identified: red-green cells and blue-yellow cells. These cells are found mainly in the lateral geniculate bodies but also among retinal ganglion cells, and they form the blobs in the visual cortex. The responses of these cells support Hering's theory of colour vision. Syn. opponent-process cell (although this term also includes a cell that increases its response to white light and decreases its response to dark). See blobs; Hering's of colour vision theory.
complex cell A cell in the visual cortex whose receptive field consists of a large responsive area, approximately rectangular in shape, surrounded by an inhibitory region. The stimulus, which is usually a slit or a straight line, gives an optimum response if appropriately orientated but falling anywhere within the excitatory area. These cells tend to respond optimally to the movement of a specifically orientated slit. Many complex cells also respond better when the optimally orientated slit is moved in one direction rather than in the opposite direction. In general, complex cells show non-linear spatial summation properties. See visual area; hypercomplex cell; simple cell; receptive field; summation.
cone cell Photoreceptor of the retina which connects with a bipolar cell and is involved in colour vision and high visual acuity and which functions in photopic vision. The outer segment of the cell is conical in shape, except in the fovea centralis where it is rod-like. In the outer segment (i.e. the part closest to the pigment epithelium) are contained hollow discs (or lamellae), the membranes of which are joined together and are also continuous with the boundary membrane of the cone cell. The visual pigments are contained in these discs. There are three types of cones, each containing a different pigment sensitive to a different part of the light spectrum. They are referred to as long-wave-sensitive (or L-cones), medium-wave-sensitive (or M-cones) and short-wave-sensitive (or S-cones). There are about six million cones in the retina, with the greatest concentration in the macular area (Fig. C4). See cone pedicle; Stiles-Crawford effect; ellipsoid; foveola; macula; visual pigment; duplicity theory; photopic vision.
fixed cell See corneal corpuscle.
ganglion cell 1. Retinal cell that connects the bipolars and other cells in the inner plexiform layer with the lateral geniculate body. The axons of the ganglion cells constitute the optic nerve fibres. There are many types of ganglion cells. The two major types are: the magno (M or parasol) ganglion cells which project mainly to the magnocellular layers of the lateral geniculate bodies; and the parvo (P) ganglion cells which project to the parvocellular layers of the lateral geniculate bodies. Two types of P ganglion cells are noted: P1, which are midget cells and have small dendritic fields and P2, which have large dendritic fields. M and P cells comprise about 10% and 82% of the ganglion cells respectively. 2. One of a collection of nerve cell bodies found in a ganglion. See C cell; M cell; P cell; melanopsin.
glial cell's Cells found throughout the nervous system. They provide support and nutrition for neurons, as well as being involved in the operation of the brain, especially the fluid surrounding the neurons and their synapses. They are also believed to be involved in the reuptake of neurotransmitters from within the synaptic cleft. There are three types of glial cells: astrocytes; microglia; oligodendroglia. Syn. glia; neuroglia.
goblet cell Cell of the conjunctival epithelium which secretes mucin. See glands of Henle; mucin; xerophthalmia.
horizontal cell Retinal cell located in the inner nuclear layer which connects several cones and rods together.
hypercomplex cell A cell in the visual cortex that receives inputs from several simple and complex cells and therefore has an even more elaborate receptive field than a complex cell. It is most effectively stimulated by a stimulus of a specific size and of a specific orientation and which is moved in a specific direction. See complex cell; simple cell.
Langerhans' cell's Dendritic cells located mainly in the epidermis, mucous membranes and lymph nodes. They have surface receptors for immunoglobulin (Fc), complement (C3) and surface HLA-DR (Ia) antigen. Langerhans' cells are also found in the conjunctival epithelium and among the basal cells, mainly of the peripheral corneal epithelium. They have antigenic functions, stimulate T-lymphocytes, prostaglandin production and participate in cutaneous delayed hypersensitivity and corneal graft rejection. Extended wear of contact lenses tends to induce an increase of these cells. They are also found in histiocytic tumours.
M cell A retinal ganglion cell, mainly located in the periphery of the retina and which assists in movement perception. M cells tend to give transient responses to stimuli and to have non-linear spatial summation properties. This cell transmits information principally to the magno cells of the lateral geniculate bodies. Syn. A cell; Pαcell; Y cell (thus called in the cat).
magno cell See ganglion cell; lateral geniculate bodies.
midget cell See ganglion cell.
Mueller's cell Neuroglial cell in the retina with its nucleus in the inner nuclear layer and with fibres extending from the external to the internal limiting membrane. These cells support the neurons of the retina and possibly assist in their metabolism. Syn. Müller cell.
orientation-specific cell A cell that responds best to specifically orientated lines. This is the case for almost all cells in the visual cortex. Examples: complex cell; simple cell. See complex cell; simple cell; receptive field.
P cell A retinal ganglion cell, mainly located in the central region of the retina and which assists in high acuity and colour vision. P cells tend to give sustained responses to stimuli and to have linear spatial summation properties. This is the most common type of ganglion cells (about 82%). This cell transmits information principally to the parvo cells of the lateral geniculate bodies. Syn. B cell; Pβcell; X cell (thus called in the cat).
parasol cell See ganglion cell.
parvo cell See ganglion cell; lateral geniculate bodies.
rod cell Photoreceptor cell of the retina which connects with a bipolar cell. It contains rhodopsin and is involved in scotopic vision. The molecules of rhodopsin are contained in about 1000 hollow discs (double lamellae or membranes), which are isolated from each other and from the boundary membrane of the rod cell. These discs are found in the outer segment (i.e. the part closest to the pigment epithelium) of the cell. There are about 100 million rod cells throughout the retina; only a small area, the foveola, is free of rods (Fig. C4). See eccentricity; ellipsoid; foveola; rhodopsin; rod spherule; duplicity theory; scotopic vision.
Schwann cell A cell whose membrane spirals around the axon with layers of myelin in between each coil, as well as being a source of the myelin sheath. The cell provides insulation to the axon. It covers about one millimetre, so that hundreds may be needed to completely cover an axon. It also allows for an increase in the speed of the nervous impulse without an increase in axonal diameter. The gaps between the segments covered by the cells are called nodes of Ranvier. See action potential.
simple cell A cell in the visual cortex whose receptive field consists of an excitatory and an inhibitory area separated by a straight line, or by a long narrow strip of one response flanked on both sides by larger regions of the opposite response. Responses occur only to a straight line or a narrow strip orientated approximately parallel to the boundary/ies between the two areas. In general, simple cells show linear spatial summation properties. They are presumably the first cells where the nervous impulses are processed as they enter the visual cortex. See visual area; complex cell; receptive field.
squamous cell See corneal epithelium.
W cell See C cell.
wing cell See corneal epithelium.
X cell See P cell.
Y cell See M cell.
)
Fig. C4 Structures of a rod and a cone cell of the retina (ELM, external limiting membrane; ONL, outer nuclear layer; OPL, outer plexiform layer)
| Table C1 distinguishing features of the two principal types of ganglion cells of the retina | ||||
| properties | P cell (X cell) | M cell (Y cell) | ||
| size of cell body | small | large | ||
| dendritic spread | small | medium/large | ||
| receptive field size | small | medium/large | ||
| retinal distribution | 90% of these at the macula | 5% of these at the macula; about 13% overall | ||
| projection | LGN parvocellular layers | LGN magnocellular layers | ||
| type of response | sustained | transient | ||
| light sensitivity | low | high | ||
| wavelength response | selective (except P cells) | non-selective | ||
| spatial sensitivity | fine target detail | large target detail | ||
| temporal sensitivity | low target velocity | high target velocity | ||
Patient discussion about Parafollicular cells.
Q. How are cancer cells similar to normal cells, and how are they different? I know that a similarity would be cells regenerate, and a difference would be cancer cells grow uncontrollably. Is there anything else?
A. I learned a lot of new things from the answers. Thanks.
Q. is there such thing bone cancer? if so what does it cause? i am asking because bone isn't a cell platform and cancer is cells that are multiplying by the dozen !!! is so also in bone , if there is such thing ...
A. hmmm...here is the picture again:
http://images.google.co.il/imgres?imgurl=http://www.siumed.edu/~dking2/ssb/images/NM036b.jpg&imgrefurl=http://www.siumed.edu/~dking2/ssb/NM036b.htm&h=471&w=600&sz=78&hl=iw&start=3&usg=__41ScizyAIOw9o5Dy7ddUqBu9Nsw=&tbnid=oqT7BPisw6NjrM:&tbnh=106&tbnw=135&prev=/images%3Fq%3Dosteocyte%26gbv%3D2%26hl%3Diw%26sa%3DX
http://images.google.co.il/imgres?imgurl=http://www.siumed.edu/~dking2/ssb/images/NM036b.jpg&imgrefurl=http://www.siumed.edu/~dking2/ssb/NM036b.htm&h=471&w=600&sz=78&hl=iw&start=3&usg=__41ScizyAIOw9o5Dy7ddUqBu9Nsw=&tbnid=oqT7BPisw6NjrM:&tbnh=106&tbnw=135&prev=/images%3Fq%3Dosteocyte%26gbv%3D2%26hl%3Diw%26sa%3DX
Q. What tests can the doctors do to see if I have cancer cells still in me? Am using my friend user name. I had a mastectomy in October of the 3cms lump. They also removed lymph nodes from armpit. They found that 2 nodes were slightly infected and 2 blood vessels leading away were the same. My oncologist says I should start chemo for 5 months followed by 5 wks of radiotherapy. I am awaiting the results from bone, heart, lungs and blood tests. What tests can the doctors do to see if I have cancer cells still in me?
A. You need to have your own self examination, which you can get guidance from doctor and all the tests which you already had and the tests which you are awaiting. Like you may have clinical examination, mammograms- which you already had, breast biopsy, ultrasonography, post biopsy pathology test, HER-2 gene test to find the speed of your tumor growth. Tests to check cancer spread – like lymph, bone, liver and lungs whose results you are waiting for.
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