| novel oxidative pathways of sulphapyridine and sulphadiazine by the turtle pseudemys scripta elegans. | the sulphonamides sulphapyridine and sulphadiazine show novel hydroxy metabolites in the turtle pseudemys scripta elegans. in the excreta of the turtles the monohydroxy metabolites 4-hydroxy- and 5-hydroxysulphapyridine and the dihydroxy metabolite 4,5-dihydroxysulphapyridine were detected. of sulphadiazine only dihydroxy metabolites 4,5- and 4,6-dihydroxysulphadiazine were detected. about 70-90% of the dose of sulphapyridine was recovered, while this figure varied between 48 and 69% for sulphad ... | 1991 | 1776236 |
| measuring the lipid content of live animals using cyclopropane gas. | the cyclopropane technique was validated, and it accurately estimated the lipid mass of six pond turtles (trachemys scripta). this technique provided more accurate estimates of lipid mass and lipid-free mass (by difference) than other nonfatal techniques. this technique was accurate despite the turtles' low lipid contents (0.71-3.5% of body mass), variable water contents (65-74% of body mass), and variable body temperatures (approximately 23-31 degrees c). a computer model of the cyclopropane te ... | 1991 | 1887962 |
| progesterone downregulates progesterone receptor, but not estrogen receptor, in the estrogen-primed oviduct of a turtle (trachemys scripta). | progesterone downregulates nuclear progesterone receptor (rp) and estrogen receptor (re) in the estrogen-primed mammalian uterus and chick oviduct. we sought to determine if this downregulation mechanism is operative in the turtle oviduct. female turtles were primed for 4 days with 17-beta-estradiol, after which progesterone (5 mg) was administered by injection every 24 h. re and rp levels in progesterone-treated and control turtle oviducts were measured by [3h]steroid-binding assays (pyridoxal ... | 1991 | 1916218 |
| o-dealkylation and n4-acetylation of sulpha-2-monomethoxine by the turtle pseudemys scripta elegans. | sulpha-2-monomethoxine is n4-acetylated to an extent of 12% of the dose by pseudemys scripta elegans; 48% is excreted unchanged. no o-dealkylation of the 2-methoxy group takes place. | 1991 | 1949545 |
| estrogen and sex reversal in turtles: a dose-dependent phenomenon. | exogenous estradiol benzoate (eb) or estradiol-17 beta (e2) caused dose-dependent gonadal feminization of slider turtle (trachemys scripta) embryos incubated at a male-producing temperature (26 degrees), suggesting that sex reversal requires a threshold dosage of these hormones. even at dosages resulting in mixtures of males and females, nearly all hatchlings had normal-appearing ovaries or testes. only 7 of 241 hatchlings had gonads that had not differentiated fully into ovaries or testes. thus ... | 1991 | 2055436 |
| chemical regulation of cerebral blood flow in turtles. | this study was performed to test the effect of the chemical composition of the blood on cerebral blood flow (cbf) regulation in turtles. the cbf response to increases in arterial pco2 (paco2) (hypercapnia) was measured during normoxia and anoxia in anesthetized freshwater turtles pseudemys scripta. the radioactive-microsphere technique was used to measure cbf. cbf increased with increases in paco2. the sensitivity of the cbf response to hypercapnia (delta cbf/delta paco2) was 0.68 ml.min-1.100 g ... | 1991 | 1899982 |
| effects of excitatory amino acids and their antagonists on the light response of luminosity and color-opponent horizontal cells in the turtle (pseudemys scripta elegans) retina. | both kainic acid (ka) and n-methyl-d-aspartatic acid (nmda) depolarize luminosity-type horizontal cells (l-type h cells) in normal turtle retina. the presence of both nmda and non-nmda receptors for excitatory amino acids (eaas) on these cells was highlighted by an unusual effect of the noncompetitive nmda-antagonist, mk-801. in retinas that had been exposed to mk-801, the action of nmda was irreversibly altered to one of hyperpolarization, while the depolarizing effect of ka was unaltered. the ... | 1991 | 1675585 |
| search for ion-cyclotron resonance in an na(+)-transport system. | colonic tissue from the turtle (pseudemys scripta) was exposed in a ussing chamber to simultaneously applied static and time-varying magnetic fields. transepithelial differences of potential were monitored as frequency of the ac field was varied continuously or in discrete steps from 3 to 770 hz. density of the dc field was varied from 10 to 220 microt and that of the ac field from 1 to 20 microt. short-circuit currents through tissue were monitored for changes that might have been observed unde ... | 1991 | 2039558 |
| the innervation of the gastrointestinal tract of a chelonian reptile, pseudemys scripta elegans. i. structure and topography of the enteric nerve plexuses using neuron-specific enolase immunohistochemistry. | the general morphological features of the intramural enteric nervous system of a chelonian species, i.e. the red-eared turtle, pseudemys scripta elegans, has been studied in whole-mounts and cryosections by means of neuron-specific enolase immunohistochemistry. a clear visualization of both neuronal cell bodies and nerve fibres allows the recognition of a myenteric plexus as well as a submucous plexus in several gut regions, namely the stomach, midgut and hindgut. the highest innervation density ... | 1991 | 2022490 |
| n2-glucuronidation and n4-acetylation of sulphaphenazole by the turtle pseudemys scripta elegans. | after an oral dose of 100 mg of sulphaphenazole, the turtle pseudemys scripta elegans excretes 27% of the compound unchanged and 3.8% as n4-acetylsulphaphenazole. the expected glucuronide conjugate, sulphaphenazole-n2-glucuronide, is not formed and excreted. | 1991 | 2021055 |
| genetic damage in a population of slider turtles (trachemys scripta) inhabiting a radioactive reservoir. | turtles inhabiting a radioactive reservoir appear to experience genetic damage due to environmental exposure to low concentrations of long-lived radionuclides. total body burdens for the 50 reservoir turtles examined in the survey ranged from 164.7-4679.3 bq for cesium-137 and from 462.6-5098.3 bq for strontium-90. flow cytometric (fcm) assays of red blood cell nuclei demonstrated significantly greater variation in dna content for the reservoir turtles than for turtles from a nearby, non-radioac ... | 1991 | 1996906 |
| ionic influences on the prolonged depolarization of turtle cones in situ. | 1. the effects of ion channel blockers and ion substitutions on the prolonged depolarization of cones in the retina of the turtle (pseudemys scripta elegans) were studied by intracellular recording. 2. the results of current injection experiments indicate that the prolonged depolarization is regenerative and accompanied by a reduction in the cone's input resistance. 3. the addition of cobalt (5-10 mm) or the removal of extracellular calcium suppressed the prolonged depolarization. raising extrac ... | 1991 | 1900325 |
| calcitonin gene-related peptide, enkephalin and serotonin coexist in neuroepithelial bodies of the respiratory tract of the red-eared turtle, pseudemys scripta elegans. an immunocytochemical study. | the lungs of the red-eared turtle, pseudemys scripta elegans, have been investigated by light-microscopical immunocytochemistry for serotonin (5-ht) and the neuropeptides calcitonin gene-related peptide (cgrp), enkephalin (enk), bombesin, somatostatin, calcitonin and cholecystokinin. cgrp- or 5-ht-like immunoreactivity (li) was demonstrated in neuroepithelial bodies (nebs) and solitary neuroepithelial endocrine cells lying between the ciliated epithelial cells of the intrapulmonary bronchi, and ... | 1991 | 1856111 |
| [the synaptic ribbons in the retina of the turtle (pseudemys scripta elegans): ultrastructural and chronobiological study]. | the authors investigate the morphology and the behaviour of the synaptic ribbons (ns) in the outer plexiform layer of the retina of the turtle pseudemys scripta elegans during the 24 hrs cycle; the animals were subjected to a light-dark cycle = 12:12 hours. new ultrastructural features are demonstrated in the rod arciform density and in the fibers connecting the central axis of the ribbon with the presynaptic membrane (figs. 1 a-b). as to chronobiological data, the existence of different kinds o ... | 2008 | 1781721 |
| the role of hormone binding in the cold suppression of hormone stimulation of the pituitary, thyroid, and testis of the turtle. | the ability of hormones to bind to their functional receptors on turtle (pseudemys scripta) endocrine target tissues in the cold was tested by treating tissues with secretagogues at low temperatures (5-15 degrees) and then following subsequent target stimulation in the absence of secretagogue at a warm temperature (28 degrees). administration of thyrotropin-releasing hormone (trh), corticotropin-releasing hormone, and growth hormone-releasing hormone to pituitaries at low temperatures (20 degree ... | 1990 | 2289680 |
| effects of synaptic blocking agents on the depolarizing responses of turtle cones evoked by surround illumination. | the effects of synaptic blocking agents on the antagonistic surround of the receptive field of cone photoreceptors were studied by intracellular recording in the retina of the turtle (pseudemys scripta elegans). illumination of a cone's receptive-field surround typically evoked a hybrid depolarizing response composed of two components: (1) the graded synaptic feedback depolarization and (2) the prolonged depolarization, a distinctive, intrinsic response of the cone. the locus of action of synapt ... | 1990 | 2085473 |
| life history and ecology of the slider turtle. j. whitfield gibbons, with contributions by harold w. avery et al. smithsonian institution press, washington, dc, 1990. xiv, 368 pp., illus. $60. | | 1990 | 17840206 |
| changes in turtle brain neurotransmitters and related substances during anoxia. | freshwater turtles (pseudemys scripta elegans) were exposed to 0.5-13 h of anoxia at 25 degrees c, whereupon the brain concentrations of 14 amino acid and monoamine neurotransmitters and related substances were measured. monoamines are of particular interest, because their synthesis and (in part) degradation require molecular oxygen. during anoxia, the level of the inhibitory transmitter gamma-aminobutyric acid (gaba) increased (2.3-fold after 13 h) and the level of the excitatory transmitter gl ... | 1990 | 1696793 |
| steroidal modulation of pituitary gonadotropin-releasing hormone responsiveness in young turtles, pseudemys scripta. | steroid-modulated pituitary secretion and glandular content of gonadotropin (gth: lh and fsh) was studied in young slider turtles. injection (ip) of both 17 beta-estradiol (e2) and testosterone (t) reduced pituitary content of both gths and caused significant inhibition of basal lh secretion and gonadotropin-releasing hormone (gnrh)-stimulated lh and fsh secretion measured in vitro. however, gonadectomy did not affect pituitary gth secretion or response in these juveniles, and anti-estrogen and ... | 1990 | 2112103 |
| distribution of [3h]mk-801 binding in the turtle retina: an autoradiographical study. | frozen sections (15 microns) of the turtle (pseudemys scripta elegans) retina were incubated in 1.6 nm [3h]mk-801. autoradiograms were generated using dry autoradiographical techniques. a band of [3h]mk-801 labelling was observed in the outer plexiform layer and cells were occasionally labelled in the inner nuclear and ganglion cell layers. this pattern of labelling was enhanced by preincubation in 1.0 mm glycine but not affected by pre-incubation in 3.0 mm n-methyl-d-aspartate (nmda). we did no ... | 1990 | 2163036 |
| membrane currents of spiking cells isolated from turtle retina. | we examined the membrane properties of spiking neurons isolated from the turtle (pseudemys scripta) retina. the cells were maintained in culture for 1-7 days and were studied with the whole cell patch clamp technique. we utilized cells whose perikaryal diameters were greater than 15 microns since kolb (1982) reported that ganglion cell perikarya in pseudemys retina are 13-25 microns, whereas amacrine perikarya are less than 14 microns in diameter. we identified 5 currents in the studied cells: ( ... | 1990 | 2388180 |
| urinary bladders of freshwater turtles as a renal physiology model potentially biased by monogenean infections. | because the urinary bladder of the freshwater red-eared slider turtle, trachemys scripta elegans, is analogous to the collecting and distal tubules of the mammalian kidney, it is used frequently as an experimental model in renal physiology. the urinary bladders of 41% of these turtles obtained over a 1 year period from a commercial supplier were infected with the monogenean parasite neopolystoma orbiculare. macroscopically, the infected bladders appeared normal, aside from the presence of adult ... | 1990 | 2157098 |
| phosphofructokinase from a vertebrate facultative anaerobe: effects of temperature and anoxia on the kinetic parameters of the purified enzyme from turtle white muscle. | the effects of low temperature and anoxia were determined on phosphofructokinase (pfk) purified from white skeletal muscle of the freshwater turtle, pseudemys scripta. these effects were assayed by comparing pfk kinetic constants measured at a high (20 degrees c) and low (6 degrees c) temperature using enzyme obtained from animals held under normoxic and anoxic conditions. when assayed at 20 degrees c, pfk from anoxic animals had a lower ka for phosphate, a lower ka for amp and showed no inhibit ... | 1990 | 2137714 |
| isolation and biological activity of a novel kinin ([thr6] bradykinin) from the turtle, pseudemys scripta. | incubation of plasma from the red-eared turtle with glass beads in the presence of the kininase inhibitor 1,10-phenanthroline resulted in activation of the kallikrein-kinin system and generation of bradykinin-like immunoreactivity. the immunoreactive material comprised a single molecular form that was purified to homogeneity by reverse phase hplc. the primary structure of the peptide was determined by automated edman degradation and fast atom bombardment mass spectrometry. the amino acid sequenc ... | 1990 | 2298179 |
| synaptic analysis of amacrine cells in the turtle retina which contain tyrosine hydroxylase-like immunoreactivity. | this study examined amacrine cells in the retina of the turtle pseudemys scripta elegans, which were labelled using an antiserum directed against tyrosine hydroxylase (an enzyme participating in catecholamine synthesis). these cells were investigated using both light and electron microscopy. labelled somata were located in the inner nuclear layer near the border of the inner plexiform layer. the dendritic arborizations of these neurons were tristratified and arborized in strata 1 and 3 and near ... | 1990 | 1972186 |
| evidence for a power law intensity code in the coupled cones of the turtle. | the hyperpolarizing responses to light were recorded intracellularly from red cones of the turtle, pseudemys scripta elegans. pairs of slit stimuli were flashed alone or together at various intensities, one slit positioned on the receptive field center and the other displaced 30 microns. the peak amplitude of the response was measured, and the results analyzed to quantify the relationship between the light intensity and the size of the neural signal evoked prior to the spatial interactions occur ... | 1990 | 2378060 |
| o-dealkylation and acetylation of sulphamethomidine by the turtle pseudemys scripta elegans. | the turtle pseudemys scripta elegans acetylates and o-dealkylates sulphamethomidine. the yield of acetylation (3.1%) is about 0.7 times greater than the yield of o-dealkylation (4.3%). | 1990 | 2321353 |
| distribution of systemic blood flow during anoxia in the turtle, chrysemys scripta. | hypoxia causes a reflex redistribution of regional blood flow in mammals that maintains delivery of oxygen to vital organs such as the brain during periods of decreased oxygen availability. the present study was performed to test if this response is developed in lower vertebrates. regional organ blood flow and arterial blood gases were measured during normoxia (room air) and anoxia (nitrogen breathing) in anesthetized turtles, chrysemys scripta. organ blood flow was measured by the distribution ... | 1989 | 2616931 |
| lack of oxidative pathways in the metabolism of sulphisomidine by the turtle pseudemys scripta elegans. | | 1989 | 2614863 |
| regulation of glycolytic enzymes during anoxia in the turtle pseudemys scripta. | the glycolytic enzymes glycogen phosphorylase, phosphofructokinase (pfk), and pyruvate kinase (pk) were assessed in liver, heart, red muscle, and white muscle of aerobic and 5-h anoxic turtles (pseudemys scripta) for changes in total activity and kinetic parameters. anoxia induced statistically significant changes in these glycolytic enzymes in each of the four organs assayed. compared with normoxic controls, anoxic liver showed a 3.3-fold increase in glycogen phosphorylase activity, a 1.5-fold ... | 1989 | 2527474 |
| mk801-induced antagonism of nmda-preferring excitatory amino acid receptors in horizontal cells of the turtle retina. | intracellular recordings were made from axon terminals of l-type horizontal cells in the turtle (pseudemys scripta elegans) retina. superfusion with ringer's solution containing 3.0 mm n-methyl-d-aspartate (nmda) or 0.2 mm kainic acid (ka) induced depolarization and reduction in the hyperpolarizing light responses of horizontal cells, consistent with an agonist effect of these excitatory amino acid (eaa) analogs on postsynaptic receptors. delivery of 0.1 mm mk801, a selective blocker of nmda-typ ... | 1989 | 2549465 |
| oxidation and o-dealkylation of sulphamonomethoxine by the turtle pseudemys scripta elegans. | sulphamonomethoxine is o-demethylated at the 6 position and oxidised at the 2 position of the pyrimidine substituent by pseudemys scripta elegans. no n4-acetylation takes place. the yield of the oxidation reaction is twice that of the o-demethylation reaction. | 1989 | 2781712 |
| o-demethylation and n4-acetylation of sulphadimethoxine by the turtle pseudemys scripta elegans. | after an oral dose of 350 mg of sulphadimethoxine, the turtle pseudemys scripta elegans o-dealkylates sulphadimethoxine at the 2- and 6-position at 38% and 19% respectively, the 2-position being favoured. acetylation of sulphadimethoxine and its hydroxy metabolites occurs for 57.4%. | 1989 | 2781704 |
| localization of gaba- and gad-like immunoreactivity in the turtle retina. | gamma-aminobutyric acid (gaba) has been reported to be an important neurotransmitter in the retinas of many species. this immunocytochemical study detailed the localization of antigens resembling gaba and glutamic acid decarboxylase (gad, an enzyme involved in the synthesis of gaba), in retinal neurons in the turtle, pseudemys scripta elegans. gaba-like immunoreactivity was present within somata in the inner and outer regions of the inner nuclear layer, within somata in the ganglion cell layer, ... | 1989 | 2487094 |
| n-oxidation, o-demethylation, and excretion of trimethoprim by the turtle pseudemys scripta elegans. | trimethoprim was excreted within one hour after being given orally to the turtle pseudemys scripta elegans. no o-demethylated or n-oxide metabolites were detected. | 1989 | 2741295 |
| relationship between respiratory state and intracardiac shunts in turtles. | injection of radioactively labeled microspheres and blood o2 analysis from central vascular sites was utilized to assess intracardiac shunts in the unanesthetized and unrestrained turtle, pseudemys scripta, at 15 degrees c. both methods indicated a simultaneously occurring right-to-left (r-l) and left-to-right (l-r) shunt during ventilation and apnea. during ventilation, the o2 method estimated a r-l shunt of 24%. in contrast, injection of microspheres during ventilation estimated a r-l shunt of ... | 1989 | 2912217 |
| excretion and metabolism of a series of xanthines by the turtle pseudemys scripta elegans. | the xanthines paraxanthine, xanthine, and uric acid are absorbed completely by the turtle pseudemys scripta elegans and metabolised presumably into co2 and nh3. no intermediate metabolites are excreted. caffeine, hydroxycaffein, theobromine, hydroxytheobromine, and hydroxypraxanthine are absorbed and excreted in different amounts or percentages of the dose administered. intermediate metabolites of these compounds are not excreted. the turtle pseudemys scripta elegans may, therefore, be ammonotel ... | 1989 | 2718350 |
| permeability of the urinary bladder of the turtle, pseudemys scripta elegans, to ammonia. | 1. the permeability of the isolated turtle urinary bladder to ammonia was investigated by varying the ratio of nh3 to nh4+ concentration in the serosal bath and measuring the flux of ammonia into the mucosal bath. 2. the permeability of the turtle bladder to nh3 was in the range of 5.4-6.1 x 10(-3) cm/sec and the permeability of the unstirred layer to nh4+ was in the range of 1.1-2.1 x 10(-5) cm/sec. 3. the flux of ammonia calculated from the permeability of nh3 can account for the decrease in m ... | 1989 | 2569373 |
| flow cytometric analysis of the effects of low-level radiation exposure on natural populations of slider turtles (pseudemys scripta). | | 1988 | 3228299 |
| organ-specific control of glycolysis in anoxic turtles. | control of glycolysis during anoxia was investigated in five organs (heart, brain, liver, and red and white skeletal muscles) of the freshwater turtle, pseudemys scripta, after 1 or 5 h of submergence in n2-bubbled water. lactate was produced as the metabolic end product, with distinct organ differences in the amount (net lactate accumulation was 2.4-fold higher in brain than white muscle) and rate (lactate production in liver dropped 16-fold after the 1st h) of lactate accumulation. atp and tot ... | 1988 | 2973250 |
| bipolar cells in the turtle retina are strongly immunoreactive for glutamate. | strong glutamate immunoreactivity was observed by both light and electron microscopy in bipolar cells of the turtle (pseudemys scripta elegans) retina after postembedding immunohistochemistry. virtually all bipolar cells showed strong labeling, on average 18 times that of the müller (glial) cells. the data suggest that both on- and off-center bipolar cells are glutamatergic. photoreceptors were also labeled, but with a labeling intensity about half that of the bipolar cells. other types of retin ... | 1988 | 2903503 |
| n-oxidation, n-demethylation, and excretion of pefloxacin by the turtle pseudemys scripta elegans. | pefloxacin is minimally absorbed by the gastrointestinal tract of the turtle pseudemys scripta elegans and then n-oxidised and n-demethylated. pefloxacin is excreted within one hour after being given orally to the turtles. | 1988 | 3218071 |
| the effects of adrenocorticotropin hormone and angiotensin ii on adrenal corticosteroid secretions in the freshwater turtle pseudemys scripta. | this study examined the effects of angiotensin ii (ang ii) and mammalian adrenocorticotropin hormone (acth) on adrenal corticosteroid secretions in the freshwater turtle, pseudemys scripta. synthetic turtle ang ii ([asp1, val5] ang ii) was infused at rates of 1, 10, and 100 ng/kg/min in conscious turtles while monitoring blood pressure (bp). one 60-min saline (0.6%) infusion preceded the ang ii infusions; two followed. blood samples were collected at 30- and 60-min intervals and the plasma was f ... | 1988 | 2846407 |
| mesencephalic innervation of the turtle retina by a single serotonin-containing neuron. | co-localization of retrograde transported nuclear yellow and serotonin immunoreactivity revealed the existence of a central serotonergic projection to the retina in the turtle pseudemys scripta elegans. this serotonergic retinopetal system consists of only one fiber originating in the contralateral caudal mesencephalon. in the retina, the fiber arborizes exclusively in the temporal hemisphere, covering about one third of the total retinal surface. interestingly this projecting area lies in the p ... | 1988 | 3185966 |
| organization of the inner plexiform layer of the turtle retina: an electron microscopic study. | we have performed a serial-section electron microscopic study of the inner plexiform layer (ipl) of the retina of the turtle pseudemys scripta elegans. a qualitative and quantitative assessment of the neuropil of the ipl has been done from photomontages taken from the linear visual streak area and peripheral retina. counts of conventional, ribbon, serial, and reciprocal synapses, of ganglion cell dendrites, and of profiles containing large, dense-cored vesicles were made in five equal-thickness ... | 1988 | 3397409 |
| anoxic brain function: molecular mechanisms of metabolic depression. | an examination of the kinetic parameters of phosphofructokinase, pyruvate kinase and glycogen phosphorylase, and the cellular concentration of fructose 2,6-bisphosphate during anoxia in the turtle pseudemys scripta showed that the total activity of glycogen phosphorylase, and the phosphofructokinase inhibition constants for citrate and atp were decreased in anoxic turtle brain. these results suggest that the ability of turtle brain to survive extended periods of anoxia is the result of metabolic ... | 1988 | 2966746 |
| neuropeptide y-immunoreactive amacrine cells in the retina of the turtle pseudemys scripta elegans. | antiserum directed against neuropeptide y selectively labeled certain amacrine cells in the turtle retina. the cell types, sizes, dendritic stratification, regional distribution, and degrees of immunolabeling were examined. the results indicated that three morphologically distinct cell types were labeled: types a, b, and c. computer rotation of digitized data from camera lucida drawings was used to study dendritic stratification. the type a somata were large (11.5 micron in diameter), well-stain ... | 1988 | 3385012 |
| planar relations of semicircular canals in awake, resting turtles, pseudemys scripta. | as part of a project aimed at elucidating mechanisms of vestibulocollic control in the red-eared turtle pseudemys scripta, we have calculated the planar relations of its semicircular canals using principal-components analysis. this information is prerequisite to understanding the pattern of canal activation that is set up by head movement of any spatial form. in addition, we have developed a method for monitoring canal orientation in an awake, behaving animal, and we have used this technique to ... | 1988 | 3266090 |
| distribution and morphology of dopaminergic amacrine cells in the retina of the turtle (pseudemys scripta elegans). | a light microscopical study of the cell types that stain by immunohistochemistry for the synthesizing enzyme for dopamine, tyrosine hydroxylase, has been performed on the retina of the turtle pseudemys scripta elegans. the immunostain can be localized to a single morphological type of amacrine cell. the cells are like a28 cells of a golgi classification. they have medium sized dendritic fields that range in diameter from 200 to 700 micron with eccentricity from the visual streak. the amacrines h ... | 1987 | 2891796 |
| caudal topographic nucleus isthmi and the rostral nontopographic nucleus isthmi in the turtle, pseudemys scripta. | isthmotectal projections in turtles were examined by making serial section reconstructions of axonal and dendritic arborizations that were anterogradely or retrogradely filled with hrp. two prominent tectal-recipient isthmic nuclei--the caudal magnocellular nucleus isthmi (imc) and the rostral magnocellular nucleus isthmi (imr)--exhibited strikingly different patterns of organization. imc cells have flattened, bipolar dendritic fields that cover a few percent of the area of the cell plate consti ... | 1987 | 3611415 |
| morphometric analysis of serotoninergic bipolar cells in the retina and its implications for retinal image processing. | the entire population of retinal serotoninergic bipolar cells in the turtle pseudemys scripta elegans was labeled by immunocytochemical methods. this allowed a systematic analysis to be made of the morphological variabilities among a functionally homogeneous neuronal population. the analyzed morphological characteristics included: size of the landolt club, size of the soma, lateral extension of the ramification within the outer plexiform layer, course of the axon across the inner nuclear layer, ... | 1987 | 3301919 |
| brain ecf ph and central chemical control of ventilation during anoxia in turtles. | the role of changes in brain extracellular fluid [h+] in the control of breathing during anoxia was studied in unanesthetized turtles, chrysemys scripta. ventilation, [minute ventilation (ve), tidal volume (vt), and breathing frequency (f)], cerebral extracellular fluid (ecf) ph, and arterial blood gases were measured at 25 degrees c during a 30-min control period (room air), 30 min of anoxia (100% n2 breathing), and 60 min of recovery (room air). ecf ph was measured in the cerebral cortex with ... | 1987 | 3578552 |
| electrophysiological properties of ependymal cells (radial glia) in dorsal cortex of the turtle, pseudemys scripta. | 1. we have investigated the electrophysiological properties of ependymal cells in the isolated dorsal cortex of the turtle, pseudemys scripta. the cell bodies of these radial glia form an epithelium at the ventricular surface, and each cell sends one or more branching processes through the cortex to the pial surface. very few non-ependymal glia exist in the dorsal cortex. 2. ependymal cells had high resting membrane potentials (-90 mv), very fast time constants and a lack of intrinsic excitabili ... | 1987 | 3116210 |
| acetylation and hydroxylation of sulphatroxazole by the turtle pseudemys scripta elegans. | | 1987 | 3109170 |
| morphological changes induced in turtle retinal neurons by exposure to 6-hydroxydopamine and 5,6-dihydroxytryptamine. | following intraocular injection of the dopamine neurotoxin 6-hydroxydopamine (10-50 micrograms on two successive days in a ringer vehicle containing ascorbate and pargyline) and an incubation period of 1 to 18 days, degeneration was noted in presumptive amacrine cells in the retina of the turtle, pseudemys scripta elegans. injection of vehicle alone produced no effect. affected perikarya initially showed swollen mitochondria, lysosomes and distended cisternae. at later stages the cells took on a ... | 1987 | 2953868 |
| non-uniform projections of granule cells to the cerebellar molecular layer. an autoradiographic tracing study in a turtle. | injections of radioactive amino acids and wheat germ agglutinin were made into the cerebellar cortex of the turtle, pseudemys scripta elegans. labeled parallel fibers were always found to project along the entire mediolateral extent of the corpus cerebelli, regardless of the location of the injection site. in fact, lateral cerebellar portions of both the ipsi- and the contralateral hemisphere often appeared more heavily labeled than intermediate regions. particularly impressive was the different ... | 1987 | 3578830 |
| wavelength discrimination in the turtle pseudemys scripta elegans. | wavelength discrimination was measured with two individuals using a behavioral training technique. the delta lambda function has three minima, indicating best discrimination at 400, 510 and at 570 nm (s2) or 600 nm (s1). in the range between 450 and 510 nm the ability to discriminate wavelengths was absent. this can be explained by the filter effect of the colored oil droplets, as indicated by a model computation. color mixture experiments revealed that the high discrimination ability at 400 nm ... | 1987 | 3445484 |
| effect of autonomic agents on renin release in the turtle, pseudemys scripta. | experiments were conducted in the freshwater turtle, pseudemys scripta, to study the effect of autonomic agents on the control of renin in this primitive species. the unique finding in these studies was that, unlike mammals, isoproterenol infusion fails to increase renin activity even though heart rate and arterial pressure patterns indicated that systemic responses were similar to that in mammals. on the other hand, acetylcholine (ach) infusion resulted in a prompt threefold elevation (p less t ... | 1986 | 3538909 |
| cone synapses with golgi-stained bipolar cells that are morphologically similar to a center-hyperpolarizing and a center-depolarizing bipolar cell type in the turtle retina. | two types of golgi-stained bipolar cells have been examined by light and electron microscopy to determine the ultrastructure of their synapses with photoreceptors and the spectral type of photoreceptor with which they connect in the retina of the turtle (pseudemys scripta elegans). we have chosen bipolar cells that correspond in morphology to a center-hyperpolarizing type (h-bipolar) and a center-depolarizing type (d-bipolar) shown in marchiafava and weiler's paper (proc. r. soc. b 208:103-113, ... | 1986 | 2428846 |
| ultrastructural features of the ventromedial region of the laminar nucleus in the red-eared turtle (chrysemys scripta elegans). | the nuclei of the torus semicircularis, in particular the laminar nucleus, have been functionally implicated in sound localization, vocalization, and mating behavior. in the red-eared turtle the ventromedial region of the laminar nucleus (containing two discrete dense cellular areas and the surrounding neuropil) was examined electron microscopically in the present study. neuronal cell bodies in the two cellular areas were different in size, shape, cytoplasmic constituents, and their relationship ... | 1986 | 3722469 |
| the name of the red-eared slider: herpetologists in slow ferment. | | 1986 | 3944975 |
| organization of motor pools supplying the cervical musculature in a cryptodyran turtle, pseudemys scripta elegans. ii. medial motor nucleus and muscles supplied by two motor nuclei. | in this paper we describe the medial motor nucleus of pseudemys cervical spinal cord and the motor pools of three neck muscles that exhibit an unusual pattern of innervation. cells of the medial motor nucleus form a longitudinal column at the dorsomedial gray/white border of the ventral horn from c1 through c8. in nissl-stained transverse sections they appear fusiform with prominent medially projecting dendrites; in hrp material these dendrites are seen to cross into the contralateral ventral fu ... | 1986 | 3944275 |
| conduction velocity, size and distribution of optic nerve axons in the turtle, pseudemys scripta elegans. | electrophysiological and morphological techniques have been used to characterize optic nerve axons in the red-eared turtle. three distinct groups of axons are identified on the basis of conduction velocity and axon diameter. the first group (t1) is a small population of axons with large diameters (2.8-4.5 microns) and mean conduction velocities of 13 m/sec. the second group (t2) is a large population of axons with medium diameters (0.4-2.8 microns) and mean conduction velocities of 3 m/sec. the ... | 1986 | 3740459 |
| influence of temperature on the co2 dissociation curve of the turtle pseudemys scripta. | carbon dioxide dissociation curves were constructed for blood of pseudemys scripta. these were shifted by temperature and cco2 was inverse to temperature at common pco2. co2 capacitance coefficients for oxygenated and deoxygenated blood (beta oxy, beta deoxy) were inverse to temperature at reported in vivo arterial pco2's as was the haldane effect. data for in vivo pco2 and hb saturation of pulmonary arterial and venous blood allowed determination of effective beta which closely reflected values ... | 1986 | 3081981 |
| cellular physiology of the turtle visual cortex: synaptic properties and intrinsic circuitry. | we have examined the synaptic physiology of the isolated dorsal cortex of the turtle, pseudemys scripta elegans. electrical stimulation of afferent pathways elicited distinct, stereotyped responses in pyramidal and stellate neurons. single shocks evoked a long-lasting barrage of excitatory postsynaptic potentials (epsps) in stellate cells, and led to a burst of several action potentials. under the same circumstances, pyramidal cells displayed a small amount of short-latency excitation, but this ... | 1986 | 2868076 |
| morphology and histochemistry of the ambiens muscle of the red-eared turtle (pseudemys scripta). | six fiber types have been described in the ambiens muscle of red-eared turtles. these include one slow oxidative type, two fast oxidative types, two fast oxidative and glycolytic types, and one fast glycolytic type. fiber types are non-randomly distributed throughout cross sections of the muscle. there is a decreasing gradient of oxidative staining and an increasing gradient of glycolytic staining along an axis from the superficial to deep regions of the muscle. the slow oxidative fibers are pre ... | 1986 | 2419576 |
| the cerebellar and vestibular nuclear complexes in the turtle. i. projections to mesencephalon, rhombencephalon, and spinal cord. | cerebellar and vestibular projections were investigated in the turtle pseudemys scripta elegans following injection of 35s-methionine into the cerebellar and vestibular nuclear complexes at various locations. fibers arising from the cerebellar nuclei were traced via the cerebellar commissure to the contralateral vestibular nuclear complex (particularly the n. vestibularis inferior and n. vestibularis ventrolateralis) and caudal rhombencephalic tegmentum. ascending projections crossing the midlin ... | 1985 | 4078046 |
| the cerebellar and vestibular nuclear complexes in the turtle. ii. projections to the prosencephalon. | prosencephalic projections from the cerebellar and vestibular nuclear complexes in the turtle pseudemys scripta elegans were investigated with anterograde tracing. following injections of 35s-methionine at various locations within the cerebellar and vestibular nuclear complexes, labeled ascending fibers were found to arise from the lateral cerebellar and the rostral (superior and/or dorsolateral) vestibular nuclei. the great majority of these fibers coursed within the ipsilateral ascending periv ... | 1985 | 2416784 |
| an immunocytochemical and ultrastructural study of the endocrine pancreas of pseudemys scripta elegans (chelonia). | immunocytochemical and ultrastructural methods have shown four cell types in the endocrine pancreas of the turtle pseudemys scripta elegans: insulin-, glucagon-, somatostatin-, and pancreatic polypeptide-immunoreactive cells. each endocrine cell type was distributed differently in the duodenal or splenic regions of the turtle pancreas. round or fusiform insulin- and glucagon-containing cells could be seen as single scattered cells which were more numerous in the duodenal regions, and the cell gr ... | 1985 | 2865192 |
| gamma-aminobutyric acid concentrations are maintained in anoxic turtle brain. | changes in gamma-aminobutyric acid (gaba) concentrations in the turtle (pseudemys scripta elegans) brain were studied in situ during prolonged anoxia. with the onset of anoxia, the well-documented rapid increases in gaba found in mammalian brains were not observed in the turtle brain. although not statistically significant, mean gaba concentrations in the turtle brain were reduced from anesthetized control values during the first 30 min of anoxia. during this initial period brain glutamate conte ... | 1985 | 4037122 |
| central chemical control of ventilation and response of turtles to inspired co2. | the role of central chemosensors in the overall ventilatory response of freshwater turtles (chrysemys scripta elegans) to the addition of co2 in inspired gas was measured. centrally mediated ventilatory responses were isolated in the unanesthetized animal by combining co2 breathing and brain ventricular perfusion with mock cerebrospinal fluid (csf) of varying acid-base status. breathing 4.5% co2 resulted in increases in both ventilatory frequency (f) and tidal volume (vt), with increases in vt p ... | 1985 | 3929630 |
| dendrite distribution of identified motoneurons in the lumbar spinal cord of the turtle pseudemys scripta elegans. | motoneurons in the turtle lumbar spinal cord were injected with hrp by electrophoresis after being electrophysiologically identified as innervating a muscle belonging to a functional group. the distribution of dendrites was studied in transverse reconstructions of 45 motoneurons, including 11 motoneurons identified as innervating knee extensor muscles, eight motoneurons innervating hip retractor and knee flexor muscles, 14 motoneurons innervating ankle and/or toe extensors and 12 motoneurons inn ... | 1985 | 4044916 |
| partitioning of body fluids and cardiovascular responses to circulatory hypovolaemia in the turtle, pseudemys scripta elegans. | investigations were conducted (1) to measure the steady state compartmentation of body fluids and (2) to assess the efficacy of blood volume and pressure maintenance during haemorrhage-induced hypovolaemia in the pond turtle, pseudemys scripta elegans. the pre-haemorrhage blood volume, as determined by tracer dilution of 51cr-labelled erythrocytes, averaged 6.89 +/- 0.33% of the body mass, and was part of comparatively large extracellular (40.2 +/- 0.70%) and total body fluid volumes (75.25 +/- ... | 1985 | 4056653 |
| synaptic organization of dorsal area of the turtle, pseudemys scripta elegans. | the dorsal ventricular ridge is a subcortical structure receiving sensory information from the thalamus in reptiles. in the red-eared turtle, pseudemys scripta elegans, it contains four cytoarchitectonic areas each characterized by distinct thalamic projections. this is an electron microscopic study of one of these, the dorsal area, which receives its thalamic input from the tectorecipient nucleus rotundus. it contains four concentric zones, internal to the ependymal zone, each of which is disti ... | 1985 | 3989865 |
| mesencephalic pathway to the retina exhibits enkephalin-like immunoreactivity. | using immunocytochemical methods it was possible to demonstrate a small number of fibers within the optic nerve of the turtle pseudemys scripta elegans exhibiting met-enkephalin-like immunoreactivity. the fibers project to the retina where they ramify within the inner plexiform layer in the region of the visual streak. retrograde labelling with nuclear yellow in combination with immunocytochemical staining revealed the origin of these fibers within visceral nuclei of the caudal mesencephalon. th ... | 1985 | 2581186 |
| tectoreticular pathways in the turtle, pseudemys scripta. ii. morphology of tectoreticular cells. | the morphology of tectoreticular neurons in turtles was examined with serial section reconstructions of neurons retrogradely filled with hrp. six classes of tectal neurons project into the three tectobulbar pathways characterized in the preceding paper (sereno, '85). (1) large multipolar neurons with somata in the central gray layers, and with moderately branched dendrites sometimes spanning over a millimeter, project into the dorsal tectobulbar pathway, tbd. their dendrites are covered with fin ... | 1985 | 3980773 |
| ultrastructure and synaptic contacts of enkephalinergic amacrine cells in the retina of turtle (pseudemys scripta). | bistratified amacrine cells of the turtle retina containing enkephalin-like immunoreactivity were examined with the electron microscope with the aid of peroxidase immunocytochemical techniques. our goal was to determine the nature and the location of the synaptic contacts of these cells and the intracellular localization of the immunoreactivity. there was a diffuse reaction product throughout the cytoplasm which coated the surfaces of all the organelles and a dense reaction product which filled ... | 1985 | 2982924 |
| localization of the na-k pump in turtle retina. | the kinetics of ouabain binding to na-k pump and the distribution of pump sites were examined in the retina of pseudemys scripta elegans. binding to retinal slices followed bimolecular kinetics characterized by a kd of 1.5 x 10(-6) m and a maximum binding capacity of 11.2 x 10(-8) mol g-1 of protein. quantitative autoradiography of slices revealed a high concentration of bound ouabain in the inner segment, outer plexiform, inner plexiform and optic nerve layers, and correspondingly, a low level ... | 1985 | 2409239 |
| spectral sensitivity of the freshwater turtle pseudemys scripta elegans: evidence for the filter-effect of colored oil droplets. | spectral sensitivity was measured in the light adapted state for two individuals (s1 and s2) of pseudemys scripta elegans using a behavioral training technique. the curves have three pronounced maxima at 450 nm, at 570 nm (s1) or 540 nm (s2), and at 640 nm. the spectral sensitivity functions can be described by the over-envelope of the effective cone sensitivity functions which are determined by the absorption spectra of the cone photopigments (lambda max at 450, 518 and 620 nm) and by the filte ... | 1985 | 4024481 |
| climbing fiber projection to the turtle cerebellum: longitudinally oriented terminal zones within the basal third of the molecular layer. | injections of various radiolabeled amino acids were made into the caudal rhombencephalic tegmentum in the turtle, pseudemys scripta elegans. in animals in which injections encompassed the entire area previously identified as the possible source of cerebellar climbing fibers, the basal portion of the molecular layer was labeled almost throughout the contralateral cerebellum. in cases of restricted injections, labeled climbing fibers terminated in quite distinct longitudinally oriented zones. cont ... | 1985 | 3974878 |
| morphological and pharmacological analysis of putative serotonergic bipolar and amacrine cells in the retina of a turtle, pseudemys scripta elegans. | using immunocytochemical methods, we have been able to demonstrate serotonin-like immunoreactivity (sli) in amacrine and bipolar cells of the turtle retina. inhibition of monoamine oxidase with pargyline drastically increases the amount of 5-hydroxytryptamine within both cell types. the indoleamine 6-hydroxytryptamine is taken up by both cell types and both types are destroyed within 10 days following intraocular injection of 5,7-dihydroxytryptamine. increasing the external potassium concentrati ... | 1985 | 3896508 |
| choline acetyltransferase-like immunoreactivity in the forebrain of the red-eared pond turtle (pseudemys scripta elegans). | choline acetyltransferase (chat) immunohistochemistry was used to map the cholinergic neurons in the forebrain of pseudemys turtles. cell bodies with chat-like immunoreactivity were seen in the septum, the nucleus of the diagonal band, and embedded within the medial and lateral forebrain bundles. the region of the medial and lateral forebrain bundles contained the greatest concentration of chat-positive neurons. virtually no chat-like immunoreactivity was seen in the areas composing the reptilia ... | 1984 | 6395936 |
| a light and fluorescence cytochemical and electron microscopic study of granule-containing cells in the intrapulmonary ganglia of pseudemys scripta elegans. | in the lung of the red-eared turtle, large numbers of intramural ganglia located in the intraparenchymal connective tissue are demonstrated. numerous cells in close proximity to the principal ganglionic neurons displayed a bright blue-white formaldehyde-induced fluorescence. microspectrofluorometric analysis revealed the presence of dopamine (da) in all cells measured. subsequent light histochemical staining of the fluorescent sections showed the da-containing cells to display argentaffinity. el ... | 1984 | 6517038 |
| efferent desensitization of auditory nerve fibre responses in the cochlea of the turtle pseudemys scripta elegans. | extracellular recordings were made from single auditory afferents in the isolated half-head of the turtle, and changes in their acoustic sensitivity were examined following electrical stimulation of the efferent fibres to the basilar papilla. short trains of efferent shocks caused a prolonged elevation of the pure tone thresholds of the auditory afferents and an abolition of their spontaneous activity. these changes could be demonstrated in a majority of recordings and without antidromic firing ... | 1984 | 6520796 |
| co-localization of neurotensin-like immunoreactivity and 3h-glycine uptake system in sustained amacrine cells of turtle retina. | amacrine cells are axonless intrinsic neurones of the vertebrate retina which have cell bodies in the proximal inner nuclear layer and processes contributing to the synaptic network of the inner plexiform layer. they receive input from bipolar, interplexiform and other amacrine cells, and synapse onto these and ganglion cells. amino acid and monoamine transmitters are found in most retinal neurones, but peptide transmitters are exclusively located in amacrine cells. only one neuropeptide, amino ... | 2015 | 6387506 |
| catecholamine- and indoleamine-containing neurons in the turtle retina. | we identified a population of presumed dopaminergic amacrine cells and populations of presumed serotonergic bipolar and amacrine cells in the retina of the turtle pseudemys scripta elegans by a combination of autoradiographic, fluorescence, and immunocytochemical techniques. antisera directed against the dopamine-synthesizing enzyme, tyrosine hydroxylase (toh), stained perikarya located at the border of inner nuclear (inl) and inner plexiform (ipl) layers. processes emitted by these cells arbori ... | 1984 | 6148363 |
| excretion rates of sulfamethoxazole and n4-acetyl-sulfamethoxazole by fresh water turtles pseudemys scripta elegans. | sulfamethoxazole and n4-acetylsulfamethoxazole are excreted by fresh water turtles pseudemys scripta elegans in a biphasic mode, characterized half-lives of 5 and 100 min. acetylation and deacetylation reactions cannot be detected below a dose of 50 mg/kg. the mass balance of the dose administered is incomplete, only 30 per cent of the dose can be recovered as parent compound and metabolite. the sulfonamides must be mainly excreted by the faeces and may be metabolized in the gastro-intestinal tr ... | 1984 | 6485242 |
| the reconnection of auditory posterior root fibers in the red-eared turtle, chrysemys scripta elegans. | the auditory portion of the eighth nerve, the posterior root, was transected in chrysemys scripta elegans. two groups of animals were allowed to survive; one for 22 days and the second for 64 days. each group was then reoperated to inject hrp into the cochlear duct and allowed to survive for an additional three days - for a total survival time of 25 days and 67 days. the 67 day survivors had hrp reaction product in the eighth nerve and the primary auditory nuclei, while the 25-day survivors did ... | 1984 | 6480526 |
| angiotensin and norepinephrine effects on isolated vascular strips from a reptile. | in order to better understand the vascular effects of angiotensin ii (aii) in lower vertebrates, the contractile responses of aortic strips from the freshwater turtle pseudemys scripta elegans were studied. circumferential strips from the left aortic arch were suspended in a tissue bath in 25 degrees c reptilian ringer's solution at ph 7.5. both [asn1,val5] aii (10(-9)-10(-5) m) and norepinephrine (ne) (10(-8)-10(-4) m) produced dose-dependent contractions. the threshold dosage for aii was betwe ... | 1984 | 6735143 |
| freeze-fracture study of the turtle lung. 2. rod-shaped particles in the plasma membrane of a mitochondria-rich pneumocyte in pseudemys (chrysemys) scripta. | in thin sections of the lung of the fresh-water turtle pseudemys (chrysemys) scripta some pneumocytes can be distinguished from the remaining pulmonary epithelial cells by a larger amount of mitochondria. in these cells the typical features of type-i and type-ii cells are absent. freeze-fracture replicas reveal rod-shaped particles in the apical plasma membrane of a small population of pneumocytes, which by cytological criteria seem to be identical with the mitochondria-rich cells observed in th ... | 1984 | 6733771 |
| characterization and quantification of peptidergic amacrine cells in the turtle retina: enkephalin, neurotensin, and glucagon. | immunocytochemical methods were used for selective labeling and characterization of amacrine cells of the turtle (pseudemys scripta elegans) retina which contained neuropeptide-like immunoreactivity (leu-enkephalin, glucagon, and neurotensin). processes of amacrine cells arborized in specific strata of the inner plexiform layer (ipl). different strata were defined in relation to the boundaries of the ipl. zero represented the strata nearest the inner nuclear layer and 100 represented the strata ... | 1983 | 6363468 |
| systemic and renal effects of angiotensin ii in the freshwater turtle pseudemys scripta elegans. | this study examined the renal and systemic effects of angiotensin ii (ang ii) in the freshwater turtle, pseudemys scripta elegans. we infused [asn1, val5]ang ii at doses of 1, 10, 100, and 500 ng x kg-1 x min-1 in conscious turtles while monitoring blood pressure, glomerular filtration rate (gfr), urine volume, and plasma and urine electrolytes. saline (0.6%) was infused for two 1-h control periods at 1 ml x kg-1 x h-1 followed by a 1-h infusion of saline with ang ii added. saline alone was then ... | 1983 | 6660329 |
| some afferent and efferent connections of the vestibular nuclear complex in the red-eared turtle pseudemys scripta elegans. | in the present study some afferent, commissural, and efferent connections of the vestibular nuclear complex in the turtle pseudemys scripta elegans were demonstrated with the hrp tracing technique. afferent projections to the vestibular nuclei were found to arise in the nucleus of the basal optic root, the interstitial nucleus of the fasciculus longitudinalis medialis, the medial and lateral cerebellar nuclei, the perihypoglossal nuclear complex, and the reticular formation. distinct commissural ... | 1983 | 6643738 |
| acetylation of sulphamethoxazole by fresh water turtles pseudemys scripta elegans. | | 1983 | 6632082 |
| functional venous admixture in the lungs of the turtle, chrysemys scripta. | pulmonary functional venous admixture was determined during forced, unidirectional ventilation with pure o2 and air. at a normal lung volume of 140 ml x kg-1, anatomical shunts (physical bypass of gas exchange surface by the blood) averaged 10% of pulmonary blood flow but it increased to 28% as lung volume declined to 30 ml x kg-1. diffusion limitation and possibly inhomogeneity in ventilation: perfusion ratio also contributed to a total functional venous admixture of about 25% at normal lung vo ... | 1983 | 6622867 |
| ultrastructure of the corpuscular nerve ending in the lymph heart of the turtle (pseudemys scripta elegans). | corpuscular nerve endings were found in the tunica externa of the lymph heart of a turtle (pseudemys scripta elegans). they consisted of axon terminals and surrounding cellular lamellae. serial thin sections of one such presumable sensory corpuscle were made and reconstructed for the three-dimensional analysis of the corpuscle, with special reference to the axon terminals. it was revealed that axon terminals ramified at several points within the corpuscle and formed varicosities of various sizes ... | 1983 | 6870488 |
| freeze-fracture study of the turtle lung. 1. intercellular junctions in the air-blood barrier of pseudemys scripta. | the air-blood barrier in the lung of the turtle pseudemys scripta was studied by means of freeze-fracture replicas in an attempt to give a detailed account on the structural organization of the intercellular junctions. between the pneumocytes, zonulae occludentes containing 4-19 strands in the apico-basal direction are present; they are considered to be physiologically very tight. in the endothelium, fasciae occludentes, i.e., discontinuous occluding junctions can be found, composed of up to 4 s ... | 1983 | 6850793 |
| a correlative light-, fluorescence- and electron-microscopic study of neuroepithelial bodies in the lung of the red-eared turtle, pseudemys scripta elegans. | neuroepithelial bodies (neb) were identified for the first time in the respiratory tract of a reptile by the use of combined morphological and histochemical methods. in the red-eared turtle, pseudemys scripta elegans, neb were found within the trabecular epithelium of the respiratory tract, mainly in the branching regions of the trabeculae. an intracellular formaldehyde-induced fluorescent compound was identified as 5-hydroxytryptamine (5-ht) by means of microspectrofluorometry. subsequent histo ... | 1983 | 6196119 |
| mesodiencephalic and other target regions of ascending spinal projections in the turtle, pseudemys scripta elegans. | ascending spinal projections were investigated in turtle pseudemys scripta elegans following injections of radioactive amino acids into the spinal cord at various levels. experiments using s35-methionine were most successful in demonstrating various mesodiencephalic target areas. ascending projections from lumbar and cervical segments terminated predominantly in caudal and lateral reticular fields including the perihypoglossal complex. these spinal regions also projected for a lesser extent to r ... | 1982 | 7161414 |
| acid-base stress and central chemical control of ventilation in turtles. | central chemical control of ventilation in turtles, chrysemys (pseudemys) scripta, has been characterized by alterations in breathing frequency (f). to assess the effects of acid-base stress on the central ventilatory response, three groups of animals were subjected to 2 h of anoxia (98% n2-2% co2), 2 h of hypercapnia (8% co2 in air), or 2 h of anoxia plus hypercapnia (92% n2-8% co2). ventilatory responses were measured continuously, and arterial blood and cerebrospinal fluid (csf) acid-base var ... | 1982 | 6818207 |