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'''Pacchioni''',''' '''Antonio. 1665-1726 Rome & Tivoli anatomist;''' '''Pacchionian bodies = arachnoid granulations (1705), q.v. | |||
'''pachymenix''' G. ''pachys '' = thick + ''menix '' = a membrane; the dura mater. | |||
'''Pacini''', Filippo. 1812-1883 Pisa & Florence anatomist; lamellated (onion-like) corpuscles of Vater-Pacini in skin (1840); tendon sheaths. | |||
'''palate '''L. ''palatum '' = roof of mouth. | |||
'''palisade''' L. ''palus '' = stake; like a fence of stakes. | |||
'''palmate folds '''cf. plicae palmatae. | |||
'''palpebral''' adj. L. ''palpebra '' = eyelid, from L. ''palpitare '' = to move quickly. | |||
'''pampiniform '''adj.''' '''L. ''pampineus '' = full of vine tendrils + ''forma '' = shape; a tangled mass of veins in spermatic cord. | |||
'''pancreas''' G. ''pan '' = all + ''kreas '' = edible flesh; a sweetbread (though less of a delicacy than the thymus); intestinal exocrine & endocrine gland. | |||
'''pancreatic islets '''small islands or''' '''clusters of endocrine cells in pancreas; cf. Langerhans. | |||
'''panniculus adiposus '''L. = a little piece of cloth, a rag + L. ''adeps '' = fat (adiposus is a L. corruption); the hypodermis (Berengarius, 1524). | |||
'''Paneth''', Josef. 1857-1890 Breslau & Vienna physiologist; P. cells (1887) = eosinophilic cells at base of intestinal crypts of Lieberkühn. | |||
'''papilla''' '''(-ae)''' L. = a teat, a nipple; a nipple-like projection, e.g., on the tonge (Malpighi, c. 1670; cf. circumvallate, filiform, foliate, fungiform, vallate); duodenal papilla (containing duodenal ampulla); optic papilla; renal papilla (Berengarius, c. 1480-1550). | |||
'''papillary '''adj.''' '''L. "; of the most superficial layer of the dermis, containing fine collagen fibres immediately under the epidermis; of cardiac muscle fibres that form eminences on the inner surface of the ventricles. | |||
'''para-''' G. = beyond, beside, near. | |||
'''paradidymis '''G. " + ''didymos '' = testicle; remains of mesonephros situated on the spermatic cord above the epididymis= organ of''' '''Giraldès, q.v.; also = organ of Waldeyer. | |||
'''paraganglion (-ia) '''G. " + ''ganglion '' = a swelling; clumps of chromaffin tissue scattered alongside sympathetic nerves in thorax and abdomen; cf. Zuckerkandl. | |||
'''parakeratin '''G. " + ''keras '' = horn; a type of keratin formed in superficial cells at sites of abrasion and rapid epithelial renewal, e.g., gingiva, tongue, tonsillar crypts, palate. | |||
'''parametrium''' G. " + ''metra '' = womb, uterus; loose, fatty connective tissue in the broad ligament around uterus. | |||
'''parathyroid '''G. " + ''thyreos '' = a shield (cf. thyroid gland); gland lying "alongside" the thyroid. | |||
'''parenchyma''' G. " + ''enkeim '' = to pour in; the essential functional cells of an organ as opposed to its stroma, q.v. (NB. the accent is on the "e", not the "y"). | |||
'''paries (-ities) '''L. ''paries '' = a wall; cf. body wall around a coelom q.v. | |||
'''parietal''' adj. L. ''parietalis '' = relating to walls; the outer region or wall as opposed to visceral. | |||
'''paroöphoron '''G. ''para '' = beside + ''öon '' = egg + ''phoros '' = bearing; minute tubules of the mesosalpinx lying adjacent to the uterine tube, derived from caudal part of embryonic mesonephros. | |||
'''parotid '''G. ''para '' = beside + ''otos '' = of the ear; a salivary gland. | |||
'''parous''' L. ''pario ''= I bear (children). | |||
'''pars '''L. = a part; a part of an organ, or structure, e.g., pars iridica retinae; pars nervosa; pars distalis, etc. | |||
'''PAS''' <U>p</U>eriodic <U>a</U>cid & <U>S</U>chiff's reagent; histochemical stain for carbohydrates involving production of aldehyde groups by initial treatment with periodic acid, then reaction of these groups with Schiff's reagent to produce a magenta colour. | |||
'''pearl ''' 1. a concretion formed around a grain of sand, etc.; 2. a small tough mass of material, e.g., a keratin pearl, an enamel pearl, a pearl of mucus in sputum. | |||
'''pectinate '''adj. L. ''pecten '' = a comb; musculi pectinati = muscular bands passing forwards from crista terminalis in wall of right atrium (including the crista, resembles a comb). | |||
'''pedicel''' L. ''pediculus '' = a little foot, dim. L. ''pes ''; stem attached to growing process; pedicles of podocytes in renal glomerulus. | |||
'''pedicle '''L. ''pediculus '' = a little foot (dim. of L. ''pes '' = a foot); stem or connecting stalk of a tumour; bony process connecting the lamina of a vertebra to its body; renal pedicle = renal "stalk". | |||
'''pellucidum''' L. ''per '' = through + ''lucere '' = to shine; translucent; e.g., zona pellucida of ovarian follicle; septum p. of brain. | |||
'''pelvis''' L. = a basin. | |||
'''penicillar''' adj. L. ''penicillum '' = a paint-brush, from L. ''penna '' = a feather; branching into many short segments, as in the penicillar arterioles of the spleen | |||
'''penis '''L. = a tail. | |||
'''pepsinogen '''G. ''pepis '' = digestion + ''gennan '' = to produce; a precusor of pepsin = enzyme that aids digestion. | |||
'''peri-''' G. = around, about. | |||
'''pericardium''' G. " + ''kardia '' = heart; of two types: visceral (covering the heart) and parietal (lining the pericardial sac). | |||
'''perichondrium''' G. " + ''chondros '' = granule, gristle, cartilage; connective tissue and cellular layer surrounding cartilage. | |||
'''pericyte''' G. " + ''kytos '' = hollow vessel; mesenchymal cell adjacent to capillaries. | |||
'''perikaryon''' G. " + ''karyon '' = nucleus; body of a nerve cell surrounding its nucleus; soma, q.v. | |||
'''perilymph '''G. " + L. ''lympha '' = clear fluid; a bastard term (from G. & L.) for fluid in bony labyrinth surrounding the membranous labyrinth; cf. endolymph. | |||
'''perimysium''' G. " + ''mys '' = muscle; connective tissue around a muscle fascicle. | |||
'''perineurium''' G. " + ''neuron '' = sinew; a lamellated sheath of connective tissue and cells around a nerve fascicle. | |||
'''periodontal ligament '''or''' membrane '''G. " + ''odons '' = tooth; fibro-elastic tissue (including Shapey's fibres) joining the tooth to its alveolar socket in the bone. | |||
'''periodontium '''G. " ; all the tissue around the root of a tooth. | |||
'''periosteum''' G. " + ''osteon '' = bone; fibrous membrane covering bone, attached to bony matrix by Sharpey's fibres. | |||
'''peripheral nervous system '''nerves and nerve cells outside the central nervous system; abb. PNS. | |||
'''peristalsis''' G. " + ''stalsis '' = a contraction, from ''stellein '' = to constrict; progressive contractile wave along body tubes (Culpeper, 1655); adj. peristaltic. | |||
'''peritoneum '''G. ''peri = ''around + '' teinein '' = to stretch around; membrane stretched around the lining of the abdominal sac and ensheathing some viscera; adj. peritoneal. | |||
'''Perls''', Max, 1843-1881 German pathologist; Perls' test for hemosiderin using the Prussian blue reaction/stain. | |||
'''Peyer''', Johann Konrad. 1653-1712 Schaffhausen, professor of Logic, Rhetoric & Natural Science; P.'s patches = aggregated lymphatic nodules in terminal ileum (1673). | |||
'''phagocytosis''' G. ''phagein '' = to eat + ''kytos '' = cell + ''osis '' = a condition of; process by which a cell engulfs foreign particles, dead material, etc. | |||
'''phalangeal ''' adj. G. ''phalanx '' = a band of soldiers (a Greek army division in battle order); phalangeal cells = sustentacular cells in organ of Corti whose processes extend upwards between the hair cells like fingers; Deiters, q.v. | |||
'''pharynx''' G. = throat; adj. pharyngeal (? G. ''pharanx '' = a cleft, chasm). | |||
'''pheomelanin '''G. ''phaios '' = dusky red + ''melas '' = black; pigment found in red hair. | |||
'''phlegm '''G. phlegma = thick mucus; one of four humours of early physiology; thought to be a discharge from brain; cf. pituitary. | |||
'''Phloxine''' red cytoplasmic dye. | |||
'''photoreceptor '''G. ''phos '' = light + L. ''recipio '' = I receive; bastard term for light-sensitive cells in retina. | |||
'''physic '''G. ''physikos '' = natural; the art of medicine. | |||
'''pia mater''' L. ''pius '' = soft, faithful (L. ''pietas '' was one of the cardinal virtues) + ''mater '' = mother; delicate vascular membrane which adheres to surface of brain and spinal cord, faithfully following their contours. | |||
'''picric acid''' a yellow dye. | |||
'''pilomotor''' L. ''pilus '' = a hair + ''motor '' = mover; causing hair movement; cf. arrector pili. | |||
'''pineal '''L. ''pinea '' = pine cone; cone-shaped gland of the brain; cf. conarium. | |||
'''pinocytosis''' G. ''pinein '' = to drink + ''kytos '' = cell + ''osis '' = a condition of; process by which a cell takes in droplets of fluid. | |||
'''pituitary '''L. ''pituita '' = phlegm, snot; gland at base of brain thought to be responsible for nasal secretion, via perforations in cribriform plate of ethmoid (Vesalius, c. 1560). | |||
'''placenta '''L. = a flat cake, from G. ''plax ''- = flat- ; (Ge. ''Mutterkuchen '' = "mother-cake" = placenta). | |||
'''plasma''' G. = a thing formed; liquid component of lymph, blood; NB. plasma membrane = cell membrane. | |||
'''plasmodium '''G. " + ''-oeides '' = like; a continuum of protoplasm in which many nuclei are embedded, e.g., placental plasmodium = syncytiotrophoblast. | |||
'''plasmolysis '''G. " + ''lysis '' = solution; shrinkage of a cell due to osmotic pressure. | |||
'''platelet''' OF. ''plate '' = flat; small, non-nucleated discoids in circulating blood derived from fragmentation of megakaryocytes. | |||
'''pleomorphic''' G. ''pleon '' = more + ''morphe '' = form; varying in shape and size. | |||
'''pleura''' '''(-ae)''' G. = rib, side; serous membrane covering lungs and lining thorax; parietal and visceral pleurae. | |||
'''plexus''' '''(-i)''' L. = a braid; a woven network of linear structures, especially nerves. | |||
'''plica''' '''(-ae)''' a corruption from L. ''plicare '' = to fold; in13th century a scalp infection endemic in Poland was called ''plica polonica '' (Polish plait); any kind of fold. | |||
'''plicae circulares '''L. = circular folds; actually transverse folds that are not circular in small intestine = valves of Kerckring, q.v. | |||
'''plicae palmatae '''L. " + ''palmatae '' = like palm trees; flat mucosal folds like palm fronds in uterine cervical canal. | |||
'''podocyte''' G. ''podos '' = foot + ''kytos '' = hollow vessel (cell); cell in renal glomerulus with many feet (foot processes) and pedicels. | |||
'''-poiesis''' G. = making or producing; suffix as in haemopoiesis, leucopoiesis. | |||
'''polar body '''the''' '''smaller daughter nucleus of a fertilised dividing ovum. | |||
'''polkissen''' Ge. = pole cushion; extraglomerular mesangial cells at vascular pole. | |||
'''polychromatophilic''' G. ''polys '' = many + ''chroma '' = colour + ''philein '' = to love. | |||
'''polymorphonuclear ('''abb.''' polymorph)''' adj. G. " + ''morphe '' = form; having a nucleus with different shapes (multiple lobes), e.g., a neutrophilic leucocyte. | |||
'''polyploid '''G. " + ''-oeides '' = form of; G. = manifold; having several sets of chromosomes; cf. diploid, haploid, aneuploid. | |||
'''polysome''' aggregation of ribosomes. | |||
'''pore '''L. ''porus '' = hole, aperture; nuclear pore = aperture in nuclear envelope. | |||
'''porta hepatis '''L. ''porta '' = door + ''hepatis '' = of liver; fissure at hilum of liver; NB. portal vein was vein entering porta hepatis. | |||
'''porta lienis '''L. ''porta '' = door + L. ''lienis '' = of the spleen; fissure at hilum of spleen. | |||
'''portal ''' adj. L. ''portare '' = to carry; of a vascular system carrying blood between infundibulum and adenohypophysis = hypothalamohypophyseal portal system. (NB. portal vein is named from L. ''porta '' = door). | |||
'''postcapillary venules '''smallest vessels which drain capillary beds into collecting venules. | |||
'''postsynaptic membrane '''region of membrane on a second cell opposite a synaptic terminal of the first cell; cf. synapse. | |||
'''prepuce ''' L. ''praeputium '' = prepuce or covering of glans penis (? from G. ''pro '' + ''posthe '' = penis; or ? L. ''puteo '' = I stink, from smell of smegma, q.v.; thus uncleanliness is figuratively termed ''praeputia ''). | |||
'''presynaptic membrane '''region of a nerve cell at the synapse of a terminal bouton; cf. synapse. | |||
'''progesterone '''G. ''pro '' = before + L. ''gerere '' = to bear; hormone from corpus luteum preparing the uterus for pregnancy. | |||
'''prophase''' G. ''pro '' = before + ''phasis '' = phase, from ''phainein '' = to appear, to show; first stage in mitosis of somatic cells. | |||
'''prostate''' G. ''pro '' = before + G. ''istanai '' = to stand, or ? L. ''statum '' = stood; standing before; male gland at base of ("before") bladder; Aristotle uses ''prostatai chirsoedeis '' = varicose prostate = seminal vesicles; Herophilus (c. 300 BC) uses ''prostatai adenoeideis '' = glandular prostate; Galen (c. 180 AD) uses ''prostatai '' for whole complex of seminal vesicles and prostate, based on animal dissections. | |||
'''protoplasm '''G. ''protos '' = first + ''plasma '' = a thing formed; living matter (Purkinje). | |||
'''proximal '''L. ''proxime '' = nearest (to the head, to a source, etc.); opposite to distal, q.v. | |||
'''psammoma ''' G. ''psammos '' = sand + ''oma '' = tumor; laminated concretions found in the pineal gland (cf. brain sand, acervulus) | |||
'''pseudopodium (-ia) '''G. ''pseudos '' = false, fraud + ''podos '' = foot; temporary extension of a cell. | |||
'''pseudostratified''' G. ''pseudos '' = false, fraud; simple epithelium where not all apical borders of cells reach lumen, thereby appearing to be stratified. | |||
'''pseudounipolar''' G. " ; of a sensory ganglion cell, bipolar in embryo, but in adult having one axon which bifurcates into a central and a peripheral branch, the peripheral branch behaving as a dendrite, q.v.; cf. bipolar. | |||
'''PTAH''' <U>p</U>hospho<U>t</U>ungstic <U>a</U>cid and <U>h</U>aematoxylin stain. | |||
'''pubes '''L. = signs of manhood; hair of genital region. | |||
'''pulmonary '''L. ''pulmo '' = lung. | |||
'''pulp '''L. ''pulpa '' = soft, fleshy; central part of a tooth; parts of spleen; central part of a finger. | |||
'''pulvinar '''L. = a cushioned couch (used by the gods); the raised posterior part of the thalamus, q.v. | |||
'''punctum lacrimale '''L. = a point + of tears; opening of lacrimal duct at inner canthus of the eye. | |||
'''pupil '''L. ''pupa '' = a girl, damsel, a doll (as in puppet); L. ''pupillae '' = small doll-like images seen mirrored in the eye, led to term ''pupilla '' for the central aperture of the iris (Cicero). | |||
'''Purkinje (Purkyne)''', Johannes Evangelista, Ritter von. 1787-1869 Breslau pathologist, Prague physiologist; famous microscopist; early use of microtome; recognized importance of fingerprints (1823); P. cells = largest cerebellar neurones with extensive dendrites (1837); P. cells = conducting heart cells (1845); P. phenomenon = casting shadows of retinal blood vessels. | |||
'''pyknotic''' G. ''pyknos '' = thick, close, compact + ''osis '' = condition; a nucleus with very condensed chromatin; a shrunken nucleus. | |||
'''pylorus''' G. ''pyle = ''a gate + '' ouros '' = a guard; a gate-keeper, a janitor; distal, sphincteric orifice of stomach (Galen, c. 180 AD). | |||
'''pyramidal cell '''G. ''pyramis '' = pyramid; cell in the cerebral cortex with a pyramid-shaped soma. | |||
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A Glossary of Histological and Micro-Anatomical Terms
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 |
Including historical origins and eponyms compiled by Dr Brian Freeman, Department of Anatomy, School of Medical Sciences, revised 2000. |
ANAT2241 Support | Histology | Histology Stains | Historic Terminology | Embryology Glossary
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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 |
Pacchioni, Antonio. 1665-1726 Rome & Tivoli anatomist; Pacchionian bodies = arachnoid granulations (1705), q.v.
pachymenix G. pachys = thick + menix = a membrane; the dura mater.
Pacini, Filippo. 1812-1883 Pisa & Florence anatomist; lamellated (onion-like) corpuscles of Vater-Pacini in skin (1840); tendon sheaths.
palate L. palatum = roof of mouth.
palisade L. palus = stake; like a fence of stakes.
palmate folds cf. plicae palmatae.
palpebral adj. L. palpebra = eyelid, from L. palpitare = to move quickly.
pampiniform adj. L. pampineus = full of vine tendrils + forma = shape; a tangled mass of veins in spermatic cord.
pancreas G. pan = all + kreas = edible flesh; a sweetbread (though less of a delicacy than the thymus); intestinal exocrine & endocrine gland.
pancreatic islets small islands or clusters of endocrine cells in pancreas; cf. Langerhans.
panniculus adiposus L. = a little piece of cloth, a rag + L. adeps = fat (adiposus is a L. corruption); the hypodermis (Berengarius, 1524).
Paneth, Josef. 1857-1890 Breslau & Vienna physiologist; P. cells (1887) = eosinophilic cells at base of intestinal crypts of Lieberkühn.
papilla (-ae) L. = a teat, a nipple; a nipple-like projection, e.g., on the tonge (Malpighi, c. 1670; cf. circumvallate, filiform, foliate, fungiform, vallate); duodenal papilla (containing duodenal ampulla); optic papilla; renal papilla (Berengarius, c. 1480-1550).
papillary adj. L. "; of the most superficial layer of the dermis, containing fine collagen fibres immediately under the epidermis; of cardiac muscle fibres that form eminences on the inner surface of the ventricles.
para- G. = beyond, beside, near.
paradidymis G. " + didymos = testicle; remains of mesonephros situated on the spermatic cord above the epididymis= organ of Giraldès, q.v.; also = organ of Waldeyer.
paraganglion (-ia) G. " + ganglion = a swelling; clumps of chromaffin tissue scattered alongside sympathetic nerves in thorax and abdomen; cf. Zuckerkandl.
parakeratin G. " + keras = horn; a type of keratin formed in superficial cells at sites of abrasion and rapid epithelial renewal, e.g., gingiva, tongue, tonsillar crypts, palate.
parametrium G. " + metra = womb, uterus; loose, fatty connective tissue in the broad ligament around uterus.
parathyroid G. " + thyreos = a shield (cf. thyroid gland); gland lying "alongside" the thyroid.
parenchyma G. " + enkeim = to pour in; the essential functional cells of an organ as opposed to its stroma, q.v. (NB. the accent is on the "e", not the "y").
paries (-ities) L. paries = a wall; cf. body wall around a coelom q.v.
parietal adj. L. parietalis = relating to walls; the outer region or wall as opposed to visceral.
paroöphoron G. para = beside + öon = egg + phoros = bearing; minute tubules of the mesosalpinx lying adjacent to the uterine tube, derived from caudal part of embryonic mesonephros.
parotid G. para = beside + otos = of the ear; a salivary gland.
parous L. pario = I bear (children).
pars L. = a part; a part of an organ, or structure, e.g., pars iridica retinae; pars nervosa; pars distalis, etc.
PAS periodic acid & Schiff's reagent; histochemical stain for carbohydrates involving production of aldehyde groups by initial treatment with periodic acid, then reaction of these groups with Schiff's reagent to produce a magenta colour.
pearl 1. a concretion formed around a grain of sand, etc.; 2. a small tough mass of material, e.g., a keratin pearl, an enamel pearl, a pearl of mucus in sputum.
pectinate adj. L. pecten = a comb; musculi pectinati = muscular bands passing forwards from crista terminalis in wall of right atrium (including the crista, resembles a comb).
pedicel L. pediculus = a little foot, dim. L. pes ; stem attached to growing process; pedicles of podocytes in renal glomerulus.
pedicle L. pediculus = a little foot (dim. of L. pes = a foot); stem or connecting stalk of a tumour; bony process connecting the lamina of a vertebra to its body; renal pedicle = renal "stalk".
pellucidum L. per = through + lucere = to shine; translucent; e.g., zona pellucida of ovarian follicle; septum p. of brain.
pelvis L. = a basin.
penicillar adj. L. penicillum = a paint-brush, from L. penna = a feather; branching into many short segments, as in the penicillar arterioles of the spleen
penis L. = a tail.
pepsinogen G. pepis = digestion + gennan = to produce; a precusor of pepsin = enzyme that aids digestion.
peri- G. = around, about.
pericardium G. " + kardia = heart; of two types: visceral (covering the heart) and parietal (lining the pericardial sac).
perichondrium G. " + chondros = granule, gristle, cartilage; connective tissue and cellular layer surrounding cartilage.
pericyte G. " + kytos = hollow vessel; mesenchymal cell adjacent to capillaries.
perikaryon G. " + karyon = nucleus; body of a nerve cell surrounding its nucleus; soma, q.v.
perilymph G. " + L. lympha = clear fluid; a bastard term (from G. & L.) for fluid in bony labyrinth surrounding the membranous labyrinth; cf. endolymph.
perimysium G. " + mys = muscle; connective tissue around a muscle fascicle.
perineurium G. " + neuron = sinew; a lamellated sheath of connective tissue and cells around a nerve fascicle.
periodontal ligament or membrane G. " + odons = tooth; fibro-elastic tissue (including Shapey's fibres) joining the tooth to its alveolar socket in the bone.
periodontium G. " ; all the tissue around the root of a tooth.
periosteum G. " + osteon = bone; fibrous membrane covering bone, attached to bony matrix by Sharpey's fibres.
peripheral nervous system nerves and nerve cells outside the central nervous system; abb. PNS.
peristalsis G. " + stalsis = a contraction, from stellein = to constrict; progressive contractile wave along body tubes (Culpeper, 1655); adj. peristaltic.
peritoneum G. peri = around + teinein = to stretch around; membrane stretched around the lining of the abdominal sac and ensheathing some viscera; adj. peritoneal.
Perls, Max, 1843-1881 German pathologist; Perls' test for hemosiderin using the Prussian blue reaction/stain.
Peyer, Johann Konrad. 1653-1712 Schaffhausen, professor of Logic, Rhetoric & Natural Science; P.'s patches = aggregated lymphatic nodules in terminal ileum (1673).
phagocytosis G. phagein = to eat + kytos = cell + osis = a condition of; process by which a cell engulfs foreign particles, dead material, etc.
phalangeal adj. G. phalanx = a band of soldiers (a Greek army division in battle order); phalangeal cells = sustentacular cells in organ of Corti whose processes extend upwards between the hair cells like fingers; Deiters, q.v.
pharynx G. = throat; adj. pharyngeal (? G. pharanx = a cleft, chasm).
pheomelanin G. phaios = dusky red + melas = black; pigment found in red hair.
phlegm G. phlegma = thick mucus; one of four humours of early physiology; thought to be a discharge from brain; cf. pituitary.
Phloxine red cytoplasmic dye.
photoreceptor G. phos = light + L. recipio = I receive; bastard term for light-sensitive cells in retina.
physic G. physikos = natural; the art of medicine.
pia mater L. pius = soft, faithful (L. pietas was one of the cardinal virtues) + mater = mother; delicate vascular membrane which adheres to surface of brain and spinal cord, faithfully following their contours.
picric acid a yellow dye.
pilomotor L. pilus = a hair + motor = mover; causing hair movement; cf. arrector pili.
pineal L. pinea = pine cone; cone-shaped gland of the brain; cf. conarium.
pinocytosis G. pinein = to drink + kytos = cell + osis = a condition of; process by which a cell takes in droplets of fluid.
pituitary L. pituita = phlegm, snot; gland at base of brain thought to be responsible for nasal secretion, via perforations in cribriform plate of ethmoid (Vesalius, c. 1560).
placenta L. = a flat cake, from G. plax - = flat- ; (Ge. Mutterkuchen = "mother-cake" = placenta).
plasma G. = a thing formed; liquid component of lymph, blood; NB. plasma membrane = cell membrane.
plasmodium G. " + -oeides = like; a continuum of protoplasm in which many nuclei are embedded, e.g., placental plasmodium = syncytiotrophoblast.
plasmolysis G. " + lysis = solution; shrinkage of a cell due to osmotic pressure.
platelet OF. plate = flat; small, non-nucleated discoids in circulating blood derived from fragmentation of megakaryocytes.
pleomorphic G. pleon = more + morphe = form; varying in shape and size.
pleura (-ae) G. = rib, side; serous membrane covering lungs and lining thorax; parietal and visceral pleurae.
plexus (-i) L. = a braid; a woven network of linear structures, especially nerves.
plica (-ae) a corruption from L. plicare = to fold; in13th century a scalp infection endemic in Poland was called plica polonica (Polish plait); any kind of fold.
plicae circulares L. = circular folds; actually transverse folds that are not circular in small intestine = valves of Kerckring, q.v.
plicae palmatae L. " + palmatae = like palm trees; flat mucosal folds like palm fronds in uterine cervical canal.
podocyte G. podos = foot + kytos = hollow vessel (cell); cell in renal glomerulus with many feet (foot processes) and pedicels.
-poiesis G. = making or producing; suffix as in haemopoiesis, leucopoiesis.
polar body the smaller daughter nucleus of a fertilised dividing ovum.
polkissen Ge. = pole cushion; extraglomerular mesangial cells at vascular pole.
polychromatophilic G. polys = many + chroma = colour + philein = to love.
polymorphonuclear (abb. polymorph) adj. G. " + morphe = form; having a nucleus with different shapes (multiple lobes), e.g., a neutrophilic leucocyte.
polyploid G. " + -oeides = form of; G. = manifold; having several sets of chromosomes; cf. diploid, haploid, aneuploid.
polysome aggregation of ribosomes.
pore L. porus = hole, aperture; nuclear pore = aperture in nuclear envelope.
porta hepatis L. porta = door + hepatis = of liver; fissure at hilum of liver; NB. portal vein was vein entering porta hepatis.
porta lienis L. porta = door + L. lienis = of the spleen; fissure at hilum of spleen.
portal adj. L. portare = to carry; of a vascular system carrying blood between infundibulum and adenohypophysis = hypothalamohypophyseal portal system. (NB. portal vein is named from L. porta = door).
postcapillary venules smallest vessels which drain capillary beds into collecting venules.
postsynaptic membrane region of membrane on a second cell opposite a synaptic terminal of the first cell; cf. synapse.
prepuce L. praeputium = prepuce or covering of glans penis (? from G. pro + posthe = penis; or ? L. puteo = I stink, from smell of smegma, q.v.; thus uncleanliness is figuratively termed praeputia ).
presynaptic membrane region of a nerve cell at the synapse of a terminal bouton; cf. synapse.
progesterone G. pro = before + L. gerere = to bear; hormone from corpus luteum preparing the uterus for pregnancy.
prophase G. pro = before + phasis = phase, from phainein = to appear, to show; first stage in mitosis of somatic cells.
prostate G. pro = before + G. istanai = to stand, or ? L. statum = stood; standing before; male gland at base of ("before") bladder; Aristotle uses prostatai chirsoedeis = varicose prostate = seminal vesicles; Herophilus (c. 300 BC) uses prostatai adenoeideis = glandular prostate; Galen (c. 180 AD) uses prostatai for whole complex of seminal vesicles and prostate, based on animal dissections.
protoplasm G. protos = first + plasma = a thing formed; living matter (Purkinje).
proximal L. proxime = nearest (to the head, to a source, etc.); opposite to distal, q.v.
psammoma G. psammos = sand + oma = tumor; laminated concretions found in the pineal gland (cf. brain sand, acervulus)
pseudopodium (-ia) G. pseudos = false, fraud + podos = foot; temporary extension of a cell.
pseudostratified G. pseudos = false, fraud; simple epithelium where not all apical borders of cells reach lumen, thereby appearing to be stratified.
pseudounipolar G. " ; of a sensory ganglion cell, bipolar in embryo, but in adult having one axon which bifurcates into a central and a peripheral branch, the peripheral branch behaving as a dendrite, q.v.; cf. bipolar.
PTAH phosphotungstic acid and haematoxylin stain.
pubes L. = signs of manhood; hair of genital region.
pulmonary L. pulmo = lung.
pulp L. pulpa = soft, fleshy; central part of a tooth; parts of spleen; central part of a finger.
pulvinar L. = a cushioned couch (used by the gods); the raised posterior part of the thalamus, q.v.
punctum lacrimale L. = a point + of tears; opening of lacrimal duct at inner canthus of the eye.
pupil L. pupa = a girl, damsel, a doll (as in puppet); L. pupillae = small doll-like images seen mirrored in the eye, led to term pupilla for the central aperture of the iris (Cicero).
Purkinje (Purkyne), Johannes Evangelista, Ritter von. 1787-1869 Breslau pathologist, Prague physiologist; famous microscopist; early use of microtome; recognized importance of fingerprints (1823); P. cells = largest cerebellar neurones with extensive dendrites (1837); P. cells = conducting heart cells (1845); P. phenomenon = casting shadows of retinal blood vessels.
pyknotic G. pyknos = thick, close, compact + osis = condition; a nucleus with very condensed chromatin; a shrunken nucleus.
pylorus G. pyle = a gate + ouros = a guard; a gate-keeper, a janitor; distal, sphincteric orifice of stomach (Galen, c. 180 AD).
pyramidal cell G. pyramis = pyramid; cell in the cerebral cortex with a pyramid-shaped soma.
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