Histology Glossary - A

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A Glossary of Histological and Micro-Anatomical Terms

Including historical origins and eponyms compiled by Dr Brian Freeman, Department of Anatomy, School of Medical Sciences, revised 2000.

Histology Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | ANAT2241 Support | Histology | Histology Stains | Embryology Glossary


Abbreviations: ( ) plural form in brackets, A. Arabic, abb. abbreviation, c. circa =about, F. French adj. adjective, G. Greek, Ge. German, cf. compare, L. Latin, dim. diminutive, NA. Nomina anatomica, q.v. which see, OF. Old French



A-band abb. of anisotropic band G. anisos = unequal + tropos = turning; meaning having not equal properties in every direction; transverse bands in living skeletal muscle which rotate the plane of polarised light, cf. I-band.


Abbé, Ernst. 1840-1905. German physicist; mathematical analysis of optics as a basis for constructing better microscopes; devised oil immersion lens; Abbé condenser.


absorption L. absorbere = to suck up.


acervulus L. = sand, gritty; brain sand (cf. psammoma body).


acetylcholine an ester of choline found in many tissue, synapses & neuromuscular junctions, where it is a neural transmitter.


acetylcholinesterase enzyme at motor end-plate responsible for rapid destruction of acetylcholine, a neurotransmitter.


acidophilic adj. L. acidus = sour + G. philein = to love; affinity for an acidic dye, such as eosin staining cytoplasmic proteins.


acinus (-i) L. = a juicy berry, a grape; applied to small, rounded terminal secretory units of compound exocrine glands that have a small lumen (adj. acinar).


acrosome G. akron = extremity + soma = body; head of spermatozoon.


actin polymer protein filament found in the intracellular cytoskeleton, particularly in the thin (I-) bands of striated muscle.


adenohypophysis G. ade = an acorn + hypophyses = an undergrowth; anterior lobe of hypophysis (cf. pituitary).


adenoid G. " + -oeides = in form of; in the form of a gland, glandular; the pharyngeal tonsil.


adipocyte L. adeps = fat (of an animal) + G. kytos = a container; cells responsible for storage and metabolism of lipids, found in white fat and brown fat.


adipose adj. L. adeps = fat + G. osis = a condition of.


adluminal adj. L. ad = towards + lumen = a hole; adjacent to lumen.


adnexa L. ad = to + nexus = bound; accessory parts of a structure, e.g., the adnexa of the eye.


adrenal L. ad = to, at + ren = kidney; the suprarenal gland.


adrenergic adj. L. " + " + G. ergon = work; applied to nerves which release "noradrenalin" (norepinephrine) at their terminals.


adventitia L. adventicius = coming from the outside; outermost connective tissual covering of an organ, e.g., the outer coat of a blood vessel is its tunica adventitia.


afferent adj. L. ad = to + ferre = to bear, carry, produce; passing towards, centripetal, e.g., sensory nerves are afferent nerves with respect to the brain and spinal cord; afferent arteriole of the renal glomerulus.


agranulocyte L. a = without; a white blood cell without large numbers of cytoplasmic granules but containing some azurophilic granules, e.g., monocyte, lymphocyte.


albicans adj. L. = whitish; e.g., corpus albicans (corpora albicantia) of the ovary.


albuginea adj. L. albus = white; firm white fibrous tissue, e.g., near the surface of the testis or ovary (first used to describe aqueous humour, then sclera, of eye).


Alcian blue commercial name for dye indicating mucins.


aldehyde fuschin purple dye for elastin.


alimentary L. alimentum = nourishment.


alpha cell acidophilic cell of adenohypophysis; acidophilic cell secreting glucagon of pancreatic islets of Langerhans


alveolus (-i) L. = a small hollow, basin or flask (dim. of alveus = a belly, tub); applied to air-cell in lungs; large terminal secretory units of some exocrine glands with relatively thin walls (cf. acinus); tooth socket; adj. alveolar.


amacrine G. a = without + makros = long; a cell in the inner nuclear layer of retina without a long (axonal) process.


ameloblast OF. esmail = enamel + G. blastos = germ; cell giving rise to tooth enamel.


amitosis G. a = without + mitos = thread; direct cell division without appearance of visible chromosomes.


amnion G. Amnion = nickname for a goddess of childbirth: Eileithyia of Amnisus (or Amnias), which was the port of the land of Knossos in Crete; amnion is also Greek for a little lamb; inner of the fetal membranes forming a thin sac around embryo or fetus, and subsequently fusing with chorion.


amoeboid G. amiobe = change + -oeides = form of; having motion like an amoeba, a protozoon which continually changes its shape; of the movements of a leucocyte.


amorphous G. a = not + morphe = form; lacking structural definition.


ampulla L. ampla = full + bulla = vase; a jar or flask; a local widening in a tube; duodenal ampulla of Vater, q.v.


amylacea cf. corpus amylaceum.


anaphase G. ana = up, back, again + phasis = phase, stage; mitotic phase where chromatids separate.


anastomosis G. " + stoma = an opening; natural communication between two vessels (adj. anastomotic).


androgen G. andros = man + gennan = to produce; male hormone.


aneuploidy G. an = without + eu = good + ploos = folded + -oeides = shape of; of a cell nucleus with more or less than the correct diploid number of chromosomes.


angiology G. angeion = a vessel + logos = study; first used to describe a surgical procedure for exposing temporal artery; later, the study of blood vessels.


Angström, Anders Jonas. 1814-1879. Swedish physicist; unit of measurement; 1 Angström (symbol Å) = 0.1 nanometer.


aniline blue A. anil, indigo plant; dye for collagen etc.


anisotropic G. anisos = unequal + tropos = a turning; having properties that are not the same in all directions; able to change the plane of polarization of light.


anlage (-n) Ge. an = on + legen = to lay, place; a primordium; an incipient structure.


ansa nephronis L. ansa = bucket handle, sandle loop + nephronis = of a nephron; hair-pin bend in the straight tubules of a nephron of the kidney; cf. Henle; also ansa subclavia; ansa hypoglossi.


ansa subclavia L. = sympathetic nerve loop passing anterior and posterior to subclavian artery.


antrum (-ra) L. = a cave, cavity; a nearly-closed cavity or bulge.


anulus (or annulus) L. = a little ring, dim. L. anus; a finger-ring; the fourth finger itself.


anulus fibrosus (anuli fibrosi or annuli fibrosi) L. = little ring of fibres; lamellae of collagen fibres surrounding nucleus pulposus of intervertebral disc.


aorta G. aeiro = I lift up (something), then G. aorter = the strap of a knapsack hung from the shoulders; a butcher's "pluck" of thoracic viscera; largest artery of the thorax (the heart being like a sac, and the aorta, a strap).


apical adj. L. = apex, tip.


apocrine G. apo = from, away + krinein = to separate; budding-off of apical cytoplasm in secretory cells.


aponeurosis G. " + neuron = tendon, sinew (later, nerve); an expanded flat connective tissue sheet to which muscle fibres are attached (Galen, 180)


apoptosis G. apo = from + ptosis = a falling off (of a leaf); naturally occurring cell death; adj. apoptotic (second p is silent).


appendix testis L. ab = from + pendere = to hang + testis = of the testis; hydatid of Morgagni, q.v.


appendix vermiformis L. ab = from + pendere = to hang + vermis = worm + forma = form; a worm-shaped attachment at the beginning of the large intestine.


appendices epiploicae L. " + G. epiploon = a net; small pockets of peritoneum filled with fat attached to the colon; cf. epiploic.


apposition L. ad = to + ponere = to set, place; placed in contiguity; juxtaposition.


appositional growth L. " ; growth on a pre-existing surface; growth at periphery.


APUD amine-precursor uptake and decarboxylation; class of endocrine cells.


aqueous humour L. aqua = water + humour = fluid; fluid of low viscosity in anterior and posterior chambers of eye.


arachnoid adj. G. arachne = spider + -oeides = form; resembling a web; first applied to scum on urine; applied to cobweb-like middle layer of the three meninges of the brain (Amsterdam, 1664).


arachnoid granulations protrusions of arachnoid into superior sagittal sinus whereby cerebrospinal fluid can pass into the blood, cf. Pacchionian bodies.


arbor vitae L. arbor = tree + vitae = of life; cedar tree; the white matter seen in a median section of the cerebellum.


arbor vitae uteri cf. palmate folds (of uterine cervical canal).


arborisation from L. arbor = tree; branching as in a tree.


area cribrosa L. area = a space + cribrum = a sieve; surface of renal papilla perforated by papillary ducts of Bellini, q.v.; cf. cribriform.


areola corruption of L. aureolus = golden; pigmented area around nipple of breast.


areolar L. areola = a small open space (dim. of L. area = a space); loose, as in loose connective tissue.


argentaffin L. argentum = silver + affinis = associated with; of cells which can reduce silver from its salts without special pretreatment; e.g., some entero-endocrine cells producing serotonin.


argyrophilic G. argyros = silver + philein = to love; of cells or structures reducing silver from its salts after special pretreatment with a reducing agent; e.g., reticular fibres.


arrector pili (arrectores pilorum) L. arrector = raiser + pilus = hair; autonomically innervated smooth muscles oriented obliquely in dermis, creating "gooseflesh".


artefact L. arte = by art + factus = made; inadvertent abnormality in tissue arising during histological processing; also artifact.


arteriole a small artery, q.v.


artery G. aer = air + terein = to keep; hence L. arteria = windpipe; arteries after death often were seen to be empty of blood, i.e., to contain air.


articular L. articulatus = a little joint (dim. of L. artus = a joint); of cartilage covering the surface of bones at synovial joints.


Asselli, Gaspar. 1581-1626. Pavia anatomist, surgeon; discoverd lacteals in 1622 during vivisection of a dog.


astrocyte G. astron = a constellation, a single star + kytos = hollow vessel (cell); star-shaped neuroglial cell.


atavistic L. atavus = great grandfather's grandfather, ancestor.


atelectasis G. a = without + telos = completion, end + ektasis = expansion; imperfect expansion, collapsed condition of lungs.


atresia G. a = without + tresis = perforation; refers to a congenital absence or closure of a normal opening.


atretic follicle an ovarian follicle that fails to mature and dies.


atrophy G. a = without + trophe = food; a wasting or reduction in organ size.


Auerbach, Leopold. 1828-1897. Breslau neuropathologist & anatomist; Auerbach's nerve plexus in external muscle layer of intestinal wall (1862).


autolysis G. auto = self + lysis = dissolution; self-digestion of cells, tissues.


autonomic G. " + nomos = law; self-controlling part of nervous system.


Avicenna 980-1073. Arabian physician; celebrated author whose book Al-qanun fi 't-tibb (Canon medicinae) was used in European universities until about 1650


axis cylinder neurite (q.v.) or axon (q.v.) of a nerve cell.


axon G. = axis; neurite or long process of a neurone, usually conducting efferent nerve signals from the cell body (soma) to the peripheral terminals of the cell; contains axoplasm.


axon hillock cone-shape region of the neuronal soma from which the axon arises.


Azure a commercial name for a type of blue dye.


azurophilic OF. azur = blue + G. philein = to love; refers to reddish-purple granules in some leucocytes when stained by Romanowsky method.</P>




Histology Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | ANAT2241 Support | Histology | Histology Stains | Embryology Glossary

Cite this page: Hill, M.A. 2017 Embryology Histology Glossary - A. Retrieved August 20, 2017, from https://embryology.med.unsw.edu.au/embryology/index.php/Histology_Glossary_-_A

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