The Experts below are selected from a list of 216 Experts worldwide ranked by ideXlab platform
Stephen M Highstein - One of the best experts on this subject based on the ideXlab platform.
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infrared photostimulation of the Crista ampullaris
The Journal of Physiology, 2011Co-Authors: Suhrud M Rajguru, Richard D. Rabbitt, Claus-peter Richter, Agnella I Matic, Stephen M Highstein, Gregory M DittamiAbstract:Non-technical summary It has been shown previously that application of short pulses of optical energy at infrared wavelengths can evoke action potentials in neurons and mechanical contraction in cardiac muscle cells. Optical stimuli are particularly attractive because of the ability to deliver focused energy through tissue without physical contact or electrical charge injection. Here we demonstrate efficacy of pulsed infrared radiation to stimulate balance organs of the inner ear, specifically to modulate the pattern of neural signals transmitted from the angular motion sensing semicircular canals to the brain. The ability to control action potentials demonstrates the potential of pulsed optical stimuli for basic science investigations and future therapeutic applications. Abstract The present results show that the semicircular canal Crista ampullaris of the toadfish, Opsanus tau, is sensitive to infrared radiation (IR) applied in vivo. IR pulse trains (∼1862 nm, ∼200 μs pulse−1) delivered to the sensory epithelium by an optical fibre evoked profound changes in phasic and tonic discharge rates of postsynaptic afferent neurons. Phasic afferent responses to pulsed IR occurred with a latency of <8 ms while tonic responses developed with a time constant (τ) of 7 ms to 10 s following the onset or cessation of the radiation. Afferents responded to direct optical radiation of the sensory epithelium but did not respond to thermal stimuli that generated nearly equivalent temperature increases of the whole organ. A subset of afferent neurons fired an action potential in response to each IR pulse delivered to the sensory epithelium, at phase-locked rates up to 96 pulses per second. The latency between IR pulses and afferent nerve action potentials was much greater than synaptic delay and spike generation, demonstrating the presence of a signalling delay interposed between the IR pulse and the action potential. The same IR stimulus applied to afferent nerve axons failed to evoke responses of similar magnitude and failed to phase-lock afferent nerve action potentials. The present data support the hypothesis that pulsed IR activates sensory hair cells, thus leading to modulation of synaptic transmission and afferent nerve discharge reported here.
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Infrared photostimulation of the Crista ampullaris
The Journal of Physiology, 2011Co-Authors: Suhrud M Rajguru, Claus-peter Richter, Agnella I Matic, Stephen M Highstein, Gregory M Dittami, Richard D. RabbittAbstract:Non-technical summary It has been shown previously that application of short pulses of optical energy at infrared wavelengths can evoke action potentials in neurons and mechanical contraction in cardiac muscle cells. Optical stimuli are particularly attractive because of the ability to deliver focused energy through tissue without physical contact or electrical charge injection. Here we demonstrate efficacy of pulsed infrared radiation to stimulate balance organs of the inner ear, specifically to modulate the pattern of neural signals transmitted from the angular motion sensing semicircular canals to the brain. The ability to control action potentials demonstrates the potential of pulsed optical stimuli for basic science investigations and future therapeutic applications. Abstract The present results show that the semicircular canal Crista ampullaris of the toadfish, Opsanus tau, is sensitive to infrared radiation (IR) applied in vivo. IR pulse trains (∼1862 nm, ∼200 μs pulse−1) delivered to the sensory epithelium by an optical fibre evoked profound changes in phasic and tonic discharge rates of postsynaptic afferent neurons. Phasic afferent responses to pulsed IR occurred with a latency of
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Infrared photostimulation of the Crista ampullaris.
The Journal of physiology, 2011Co-Authors: Suhrud M Rajguru, Claus-peter Richter, Agnella I Matic, Gay R Holstein, Stephen M Highstein, Gregory M Dittami, Richard D. RabbittAbstract:The present results show that the semicircular canal Crista ampullaris of the toadfish, Opsanus tau, is sensitive to infrared radiation (IR) applied in vivo. IR pulse trains (∼1862 nm, ∼200 μs pulse⁻¹) delivered to the sensory epithelium by an optical fibre evoked profound changes in phasic and tonic discharge rates of postsynaptic afferent neurons. Phasic afferent responses to pulsed IR occurred with a latency of
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γ aminobutyric acid is present in a spatially discrete subpopulation of hair cells in the Crista ampullaris of the toadfish opsanus tau
The Journal of Comparative Neurology, 2004Co-Authors: Giovanni Martinelli, Richard D. Rabbitt, Stephen M Highstein, V. L. Friedrich, Scott C HendersonAbstract:Although γ-aminobutyric acid (GABA) and glutamate are known to be present in the vestibular sensory epithelia of a variety of species, the functional relationship between these two transmitters is not clear. The present study addresses the three-dimensional spatial distribution of GABA and glutamate immunoreactivity in the vestibular labyrinth of the oyster toadfish by using whole end organs labeled by immunofluorescence with monoclonal anti-GABA and/or antiglutamate antibodies and visualized as whole mounts by multiphoton confocal microscopy. We find glutamate-immunoreactive hair cells present throughout the sensory epithelium. In contrast, prominent GABA immunoreactivity is restricted to a small population of hair cells located in the central region of the Crista. Double immunofluorescence reveals two distinct staining patterns in GABA-labeled hair cells. Most (∼80%) GABA-labeled cells show trace levels of glutamate, appropriate for the metabolic/synthetic role of cytoplasmic glutamate. The remainder of the GABA-stained cells contain substantial levels of both GABA and glutamate, suggesting transmitter colocalization. In the toadfish utricle, glutamatergic hair cells are present throughout the macula. GABA-immunoreactive hair cells follow the arc of the striola, and most GABA-labeled receptor cells coexpress glutamate. The localization of GABA was explored in other species as well. In the pigeon, GABAergic hair cells are present throughout the Crista ampullaris. Our findings demonstrate that multiple, neurochemically distinct types of hair cells are present in vestibular sensory epithelia. These observations, together with the excitatory activity generally associated with 8th nerve afferent fibers, strongly suggest that GABA serves an important, specific, and complex role in determining primary afferent response dynamics. J. Comp. Neurol. 471:1–10, 2004. © 2004 Wiley-Liss, Inc.
Richard D. Rabbitt - One of the best experts on this subject based on the ideXlab platform.
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Developmental GAD2 Expression Reveals Progenitor-like Cells with Calcium Waves in Mammalian Crista ampullaris.
iScience, 2020Co-Authors: Holly A. Holman, Yong Wan, Richard D. RabbittAbstract:Summary Sense of motion, spatial orientation, and balance in vertebrates relies on sensory hair cells in the inner ear vestibular system. Vestibular supporting cells can regenerate hair cells that are lost from aging, ototoxicity, and trauma, although not all factors or specific cell types are known. Here we report a population of GAD2-positive cells in the mouse Crista ampullaris and trace GAD2 progenitor-like cells that express pluripotent transcription factors SOX2, PROX1, and CTBP2. GAD2 progenitor-like cells organize into rosettes around a central branched structure in the eminentia cruciatum (EC) herein named the EC plexus. GCaMP5G calcium indicator shows spontaneous and acetylcholine-evoked whole-cell calcium waves in neonatal and adult mice. We present a hypothetical model that outlines the lineage and potential regenerative capacity of GAD2 cells in the mammalian vestibular neuroepithelium.
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infrared photostimulation of the Crista ampullaris
The Journal of Physiology, 2011Co-Authors: Suhrud M Rajguru, Richard D. Rabbitt, Claus-peter Richter, Agnella I Matic, Stephen M Highstein, Gregory M DittamiAbstract:Non-technical summary It has been shown previously that application of short pulses of optical energy at infrared wavelengths can evoke action potentials in neurons and mechanical contraction in cardiac muscle cells. Optical stimuli are particularly attractive because of the ability to deliver focused energy through tissue without physical contact or electrical charge injection. Here we demonstrate efficacy of pulsed infrared radiation to stimulate balance organs of the inner ear, specifically to modulate the pattern of neural signals transmitted from the angular motion sensing semicircular canals to the brain. The ability to control action potentials demonstrates the potential of pulsed optical stimuli for basic science investigations and future therapeutic applications. Abstract The present results show that the semicircular canal Crista ampullaris of the toadfish, Opsanus tau, is sensitive to infrared radiation (IR) applied in vivo. IR pulse trains (∼1862 nm, ∼200 μs pulse−1) delivered to the sensory epithelium by an optical fibre evoked profound changes in phasic and tonic discharge rates of postsynaptic afferent neurons. Phasic afferent responses to pulsed IR occurred with a latency of <8 ms while tonic responses developed with a time constant (τ) of 7 ms to 10 s following the onset or cessation of the radiation. Afferents responded to direct optical radiation of the sensory epithelium but did not respond to thermal stimuli that generated nearly equivalent temperature increases of the whole organ. A subset of afferent neurons fired an action potential in response to each IR pulse delivered to the sensory epithelium, at phase-locked rates up to 96 pulses per second. The latency between IR pulses and afferent nerve action potentials was much greater than synaptic delay and spike generation, demonstrating the presence of a signalling delay interposed between the IR pulse and the action potential. The same IR stimulus applied to afferent nerve axons failed to evoke responses of similar magnitude and failed to phase-lock afferent nerve action potentials. The present data support the hypothesis that pulsed IR activates sensory hair cells, thus leading to modulation of synaptic transmission and afferent nerve discharge reported here.
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Infrared photostimulation of the Crista ampullaris
The Journal of Physiology, 2011Co-Authors: Suhrud M Rajguru, Claus-peter Richter, Agnella I Matic, Stephen M Highstein, Gregory M Dittami, Richard D. RabbittAbstract:Non-technical summary It has been shown previously that application of short pulses of optical energy at infrared wavelengths can evoke action potentials in neurons and mechanical contraction in cardiac muscle cells. Optical stimuli are particularly attractive because of the ability to deliver focused energy through tissue without physical contact or electrical charge injection. Here we demonstrate efficacy of pulsed infrared radiation to stimulate balance organs of the inner ear, specifically to modulate the pattern of neural signals transmitted from the angular motion sensing semicircular canals to the brain. The ability to control action potentials demonstrates the potential of pulsed optical stimuli for basic science investigations and future therapeutic applications. Abstract The present results show that the semicircular canal Crista ampullaris of the toadfish, Opsanus tau, is sensitive to infrared radiation (IR) applied in vivo. IR pulse trains (∼1862 nm, ∼200 μs pulse−1) delivered to the sensory epithelium by an optical fibre evoked profound changes in phasic and tonic discharge rates of postsynaptic afferent neurons. Phasic afferent responses to pulsed IR occurred with a latency of
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Infrared photostimulation of the Crista ampullaris.
The Journal of physiology, 2011Co-Authors: Suhrud M Rajguru, Claus-peter Richter, Agnella I Matic, Gay R Holstein, Stephen M Highstein, Gregory M Dittami, Richard D. RabbittAbstract:The present results show that the semicircular canal Crista ampullaris of the toadfish, Opsanus tau, is sensitive to infrared radiation (IR) applied in vivo. IR pulse trains (∼1862 nm, ∼200 μs pulse⁻¹) delivered to the sensory epithelium by an optical fibre evoked profound changes in phasic and tonic discharge rates of postsynaptic afferent neurons. Phasic afferent responses to pulsed IR occurred with a latency of
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γ aminobutyric acid is present in a spatially discrete subpopulation of hair cells in the Crista ampullaris of the toadfish opsanus tau
The Journal of Comparative Neurology, 2004Co-Authors: Giovanni Martinelli, Richard D. Rabbitt, Stephen M Highstein, V. L. Friedrich, Scott C HendersonAbstract:Although γ-aminobutyric acid (GABA) and glutamate are known to be present in the vestibular sensory epithelia of a variety of species, the functional relationship between these two transmitters is not clear. The present study addresses the three-dimensional spatial distribution of GABA and glutamate immunoreactivity in the vestibular labyrinth of the oyster toadfish by using whole end organs labeled by immunofluorescence with monoclonal anti-GABA and/or antiglutamate antibodies and visualized as whole mounts by multiphoton confocal microscopy. We find glutamate-immunoreactive hair cells present throughout the sensory epithelium. In contrast, prominent GABA immunoreactivity is restricted to a small population of hair cells located in the central region of the Crista. Double immunofluorescence reveals two distinct staining patterns in GABA-labeled hair cells. Most (∼80%) GABA-labeled cells show trace levels of glutamate, appropriate for the metabolic/synthetic role of cytoplasmic glutamate. The remainder of the GABA-stained cells contain substantial levels of both GABA and glutamate, suggesting transmitter colocalization. In the toadfish utricle, glutamatergic hair cells are present throughout the macula. GABA-immunoreactive hair cells follow the arc of the striola, and most GABA-labeled receptor cells coexpress glutamate. The localization of GABA was explored in other species as well. In the pigeon, GABAergic hair cells are present throughout the Crista ampullaris. Our findings demonstrate that multiple, neurochemically distinct types of hair cells are present in vestibular sensory epithelia. These observations, together with the excitatory activity generally associated with 8th nerve afferent fibers, strongly suggest that GABA serves an important, specific, and complex role in determining primary afferent response dynamics. J. Comp. Neurol. 471:1–10, 2004. © 2004 Wiley-Liss, Inc.
Ivo Prigioni - One of the best experts on this subject based on the ideXlab platform.
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Plasma membrane Ca2+-ATPase isoforms in frog Crista ampullaris: identification of PMCA1 and PMCA2 specific splice variants.
Hearing research, 2007Co-Authors: Mariarosa Polimeni, Ivo Prigioni, Giancarlo Russo, Daniela Calzi, Luciana GioglioAbstract:Abstract Ca2+ ions play a pivotal role in inner ear hair cells as they are involved from the mechano-electrical transduction to the transmitter release. Most of the Ca2+ that enters into hair cells via mechano-transduction and voltage-gated channels is extruded by the plasma membrane Ca2+-ATPases (PMCAs) that operate in both apical and basal cellular compartments. Here, we determined the identity and distribution of PMCA isoforms in frog Crista ampullaris: we showed that PMCA1, PMCA2 and PMCA3 are expressed, while PMCA4 appears to be negligible. We also identify PMCA1bx, PMCA2av and PMCA2bv as the major splice variants produced from PMCA1 and PMCA2 genes. PMCA2av appears to be the major Ca2+-pump operating at the apical pole of the cell, even if PMCA1b is also expressed in the stereocilia. PMCA1bx is, instead, the principal PMCA of hair cell basolateral compartment, where it is expressed together with PMCA2 (probably PMCA2bv) and PMCA3. Frog Crista ampullaris hair cells lack a Na/Ca exchanger, therefore PMCAs are the only mechanism of Ca2+ extrusion. The coexpression of specific isozymes in the different cellular compartments responds to the need of a fine regulation of both basal and dynamic Ca2+ levels at the apical and basal pole of the cell.
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Gradients of expression of calcium and potassium currents in frog Crista ampullaris
Pflugers Archiv : European journal of physiology, 2001Co-Authors: Giancarlo Russo, Walter Marcotti, Andrea Lelli, Ivo PrigioniAbstract:In the present work we studied the intraregional expression of voltage-dependent Ca2+ and K+ currents in hair cells of frog Crista ampullaris. The currents were recorded in situ from sensory cells of the peripheral region, the most populated region of the Crista, by using the whole-cell variant of the patch-clamp technique. Voltage-clamp recordings revealed that the calcium current (ICa) and the outward potassium currents of IA, IK, IKCa types and the inward rectifier potassium current of IK1 type exhibited a significant gradient of density (pA/pF) along the region. IA density was maximal in cells located at the beginning of the peripheral region and decreased gradually becoming very small at the opposite end. All the other currents showed an opposite gradient of expression. Current-clamp experiments showed that the voltage behaviour of hair cells changed in relation to cell position. Cells located at the beginning of the peripheral region showed large depolarizations from the resting potential (close to –45 mV) which are consistent with the presence of small IK and IKCa, and an IA largely inactivated at rest. These cells also exhibited slowly developing and large hyperpolarizations that approached passive ones, due to the lack of IK1. In contrast, cells located at the opposite side of the region showed smaller depolarizations and hyperpolarizations from the resting potential (close to –65 mV), due to the presence of large IK and IKCa, and IK1, respectively. The possible role of the intraregional variation of Ca2+ and K+ currents in both hair cell function and afferent discharge properties is discussed.
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Inactivating and non-inactivating delayed rectifier K+ currents in hair cells of frog Crista ampullaris
Hearing Research, 1999Co-Authors: Walter Marcotti, Giancarlo Russo, Ivo PrigioniAbstract:The possible presence of different types of delayed rectifier K+ current (I(K)) was studied in vestibular hair cells of frog semicircular canals. Experiments were performed in thin slice preparations of the whole Crista ampullaris and recordings were made using the whole-cell patch-clamp technique. We found that an apparent homogeneous I(K), isolated from the other K+ currents, could be pharmacologically separated into two complementary components: a capsaicin-sensitive current (I(Kc)) and a barium-sensitive current (I(K,b)). I(K,c) was recruited at potentials more positive than -60 mV and showed a slow activation having a time constant (tau(a)) ranging on average from 12 ms at 40 mV to 32 ms at -20 mV. This current inactivated slowly with two voltage-independent time constants (ta(d1) and tau(d2) were 300 ms and 4 s respectively) and more than 80% of the channels were in an inactivated state at the cell resting potential. I(K,b) was also recruited at potentials more positive than -60 mV, but in contrast to I(K,c), it activated more rapidly (tau(a) ranged on average from 1 ms at 40 mV to 4.5 ms at -20 mV) and it did not exhibit any inactivation process. Current clamp experiments revealed that I(K,b), at variance with I(K,c), contributes to the cell resting potential and represents the main repolarizing current when sensory cells are depolarized from rest. I(K,c) could have a role in hair cells when they are depolarized after hyperpolarizing stimuli, a condition that removes channel inactivation.
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Inactivating and non-activating delayed rectifier K+ currents in hair cells of frog Crista ampullaris.
Hearing research, 1999Co-Authors: Walter Marcotti, Giancarlo Russo, Ivo PrigioniAbstract:The possible presence of different types of delayed rectifier K+ current (I(K)) was studied in vestibular hair cells of frog semicircular canals. Experiments were performed in thin slice preparations of the whole Crista ampullaris and recordings were made using the whole-cell patch-clamp technique. We found that an apparent homogeneous I(K), isolated from the other K+ currents, could be pharmacologically separated into two complementary components: a capsaicin-sensitive current (I(Kc)) and a barium-sensitive current (I(K,b)). I(K,c) was recruited at potentials more positive than -60 mV and showed a slow activation having a time constant (tau(a)) ranging on average from 12 ms at 40 mV to 32 ms at -20 mV. This current inactivated slowly with two voltage-independent time constants (ta(d1) and tau(d2) were 300 ms and 4 s respectively) and more than 80% of the channels were in an inactivated state at the cell resting potential. I(K,b) was also recruited at potentials more positive than -60 mV, but in contrast to I(K,c), it activated more rapidly (tau(a) ranged on average from 1 ms at 40 mV to 4.5 ms at -20 mV) and it did not exhibit any inactivation process. Current clamp experiments revealed that I(K,b), at variance with I(K,c), contributes to the cell resting potential and represents the main repolarizing current when sensory cells are depolarized from rest. I(K,c) could have a role in hair cells when they are depolarized after hyperpolarizing stimuli, a condition that removes channel inactivation.
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Localization of Ca-ATPase in frog Crista ampullaris.
Neuroreport, 1998Co-Authors: Luciana Gioglio, Walter Marcotti, Giancarlo Russo, Ivo PrigioniAbstract:The distribution of Ca-ATPase in frog Crista ampullaris was mapped ultracytochemically by using a one-step lead citrate reaction. Electron-dense precipitates, as an expression of Ca-ATPase activity, were observed on the surface of stereocilia and on the apical membrane surrounding the cuticular plate of hair cells. Sensory cells of the isthmus region showed more reactivity than those of the peripheral regions of the Crista. No reaction products were detectable on the basolateral membranes and in cytoplasmatic organelles. Supporting cells of the Crista showed a quite variable Ca-ATPase reaction on microvilli and on basolateral membranes. The presence of an evident reactivity on the stereocilia is consistent with the existence of an apical calcium microdomain involved in the mechano-transduction process and supports the current view that calcium ions enter the stereocilia during natural stimulation. On the other hand, the lack of an observable reactivity on the basolateral membrane of hair cells suggests that in semicircular canals other mechanisms of active transport of calcium ions across the plasma membrane, such as Na-Ca exchange, may be involved in homeostasis of the ion.
G. R. Holstein - One of the best experts on this subject based on the ideXlab platform.
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Synapsin-like immunoreactivity is present in hair cells and efferent terminals of the toadfish Crista ampullaris
Experimental Brain Research, 2005Co-Authors: G. R. Holstein, G. P. Martinelli, R. A. Nicolae, T. M. Rosenthal, V. L. FriedrichAbstract:The synapsins are presynaptic membrane-associated proteins involved in neurotransmitter release. They are differentially expressed in tissues and cells of the central and peripheral nervous system. In vestibular end organs of mammals, synapsin I-like immunoreactivity has been reported in efferent and afferent terminals and in afferent nerve calyces surrounding type I hair cells. In addition, synapsin I has recently been described in several non-neural cell lines. The present study was conducted to locate synapsin-like immunoreactivity in the neuronal and non-neuronal cells of the fish Crista ampullaris, to examine the possibility that the non-neuronal sensory receptor cells express synapsins in vivo. Synapsin-like immunostaining was visualized by immunofluorescence detection in wholemounts of the toadfish Crista ampullaris using multiphoton laser scanning microscopy and by electron microscopic visualization of post-embedding immunogold labeling. The results demonstrate that synapsin-like immunoreactivity is present in vestibular hair cells and efferent boutons of the toadfish Crista ampullaris. Afferent endings are not labeled. Staining in hair cells is not associated with the synaptic ribbons, suggesting that there is an additional, non-synaptic role for the synapsins in some non-neuronal cells of vertebrates. Moreover, while the Cristae of amniote and anamniote species share many functional attributes, differences in their synaptic vesicle-associated protein profiles appear to reflect their disparate hair cell populations.
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Ultrastructural observations of efferent terminals in the Crista ampullaris of the toadfish, opsanus tau
Experimental Brain Research, 2004Co-Authors: G. R. Holstein, G. P. Martinelli, R. Boyle, R. D. Rabbitt, S. M. HighsteinAbstract:The present study was conducted to visualize the ultrastructural features of vestibular efferent boutons in the oyster toadfish, Opsanus tau. The Crista ampullaris of the horizontal semicircular canal was processed for and examined by routine transmission electron microscopy. The results demonstrate that such boutons vary in size and shape, and contain a heterogeneous population of lucent vesicles with scattered dense core vesicles. Efferent contacts with hair cells are characterized by local vesicle accumulations in the presynaptic terminal and a subsynaptic cistern in the postsynaptic region of the hair cell. Serial efferent to hair cell to afferent synaptic arrangements are common, particularly in the central portion of the Crista. However, direct contacts between efferent terminals and afferent neurites were not observed in our specimens. The existence of serial synaptic contacts, often with a row of vesicles in the efferent boutons lining the efferent-afferent membrane apposition, suggests that the efferent influence on the Crista may involve both synaptic and nonsynaptic, secretory mechanisms. Further, it is suggested that differences in more subtle aspects of synaptic architecture and/or transmitter and receptor localization and interaction may render the efferent innervation of the peripheral Crista less effective in influencing sensory processing.
Francesco Marmo - One of the best experts on this subject based on the ideXlab platform.
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Evidence for hair cell regeneration in the Crista ampullaris of the lizard Podarcis sicula.
Hearing Research, 2003Co-Authors: Bice Avallone, Giuseppe Balsamo, Maria Porritiello, Daniela Esposito, Rosalia Mutone, Francesco MarmoAbstract:We studied hair cell regeneration in the Crista ampullaris of the lizard Podarcis sicula both in untreated animals and at early and late time intervals following a single high dose of gentamicin. The study was carried out using the S-phase marker 5-bromo-2'-deoxyuridine. Our ultrastructural and immunofluorescence studies showed that both apoptosis and hair cell regeneration happen in the lizard Crista ampullaris in untreated animals, and that regenerative processes are greatly accelerated after treatment with the aminoglycoside antibiotic gentamicin. Our observations indicate that hair cell regeneration is strongly implicated in the repair of damaged sensory epithelium, and that new hair cells appear likely to arise from supporting cells.
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Evidence for hair cells regeneration in the Crista ampullaris of the lizard Podarcis sicula
'Elsevier BV', 2003Co-Authors: B. Avallone, Daniela Esposito, Maria Porritiello, G. Balsamo, Francesco MarmoAbstract:We studied hair cell regeneration in the Crista ampullaris of the lizard Podarcis sicula both in untreated animals and at early and late time intervals following a single high dose of gentamicin. The study was carried out using the S-phase marker 5-bromo-2Pdeoxyuridine. Our ultrastructural and immunofluorescence studies showed that both apoptosis and hair cell regeneration happen in the lizard Crista ampullaris in untreated animals, and that regenerative processes are greatly accelerated after treatment with the aminoglycoside antibiotic gentamicin. Our observations indicate that hair cell regeneration is strongly implicated in the repair of damaged sensory epithelium, and that new hair cells appear likely to arise from supporting cell
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Immunocytochemistry of carbonic anhydrase and non-radioactive detection of its RNA by in situ hydridization in the chick embryo membranous labyrinth.
European journal of histochemistry : EJH, 1994Co-Authors: Giuseppe Balsamo, Bice Avallone, L Rocco, Francesco MarmoAbstract:An immunocytochemical study was carried out with the aim to localize carbonic anhydrase isozymes (CA I and CA II) in the chick membranous labyrinth. CA I and CA II were localized in the same cells and, during the early developmental stages, were diffusely present in the labyrinthine epithelium. At later stages, the sensorial epithelium of the maculae acusticae, Crista ampullaris and papilla basilaris, as well as labyrinthine dark cells and the epithelium of the endolymphatic sac strongly stained by the immunocytochemical procedure. In 1-day and 1-week old chicks, CA was present in the same sites as at advanced embryonal stages. In order to detect mRNA for carbonic anhydrase II, in situ hybridization was also used. Strong hybridization signals were observed in the sensorial epithelium of the saccule, utricle and Crista ampullaris, in the tegmentum vasculosum, the endolymphatic sac, the erythrocytes and the choroid plexus in embryos older than 10 days. This positivity persisted until the day after hatching. The authors discuss the significance of labyrinthine CA and, based on in situ hybridization results, suggest that melanocytes do not provide labyrinthine dark cells with enzyme protein.