Biomedical subjects

M Vater

Publications and source records attributed to M Vater.

At least 19 recordsLinked to original sources

PubMed2006

The prognostic impact of successful cardioversion of atrial fibrillation in patients with organic heart disease.

The aim of the study was to evaluate the prognostic impact of successful cardioversion (CV) compared to failed CV in patients with atrial fibrillation (AF) and organic heart disease. A total of 471 consecutive patients with organic heart disease from the prospective single center anticoagulation registry ANTIK who underwent CV of AF or atrial flutter were analyzed. 417 patients (89%) could be successfully cardioverted. In 54 patients (11%) CV failed, these patients remained in AF. After 5 years there were 92 (24%) deaths among patients with restored sinus rhythm at index admission and 20 (38%) deaths among those who remained in AF after CV (unadjusted OR 1.9, 95% CI 1.1-3.6). After adjustment for age, gender and ejection fraction, successful CV was not associated with a beneficial effect on mortality (OR 0.72, 95% CI 0.43-1.21). Thus, successful CV is not an independent predictor of mortality on multivariate analysis. However, it remains a marker for a better prognosis in patients with organic heart disease as these patients have a lower unadjusted longterm mortality.

Aged↗

PubMed2004

Specializations for aerial hawking in the echolocation system of Molossus molossus (Molossidae, Chiroptera).

While searching for prey, Molossus molossus broadcasts narrow-band calls of 11.42 ms organized in pairs of pulses that alternate in frequency. The first signal of the pair is at 34.5 kHz, the second at 39.6 kHz. Pairs of calls with changing frequencies were only emitted when the interpulse intervals were below 200 ms. Maximum duty cycles during search phase are close to 20%. Frequency alternation of search calls is interpreted as a mechanism for increasing duty cycle and thus the temporal continuity of scanning, as well as increasing the detection range. A neurophysiological correlate for the processing of search calls was found in the inferior colliculus. 64% of neurons respond to frequencies in the 30- to 40-kHz range and only in this frequency range were closed tuning curves found for levels below 40 dB SPL. In addition, 15% of the neurons have double-tuned frequency-threshold curves with best thresholds at 34 and 39 kHz. Differing from observations in other bats, approach calls of M. molossus are longer and of higher frequencies than search calls. Close to the roost, the call frequency is increased to 45.0-49.8 kHz and, in addition, extremely broadband signals are emitted. This demonstrates high plasticity of call design.

Acoustic Stimulation↗

PubMed2003

Postnatal development of cochlear function in the mustached bat, Pteronotus parnellii.

Postnatal development of the mustached bat's cochlea was studied by measuring cochlear microphonic and compound action potentials. In adults, a cochlear resonance is involved in enhanced tuning to the second harmonic constant frequency component (CF2) of their echolocation calls at approximately 61 kHz This resonance is present immediately after birth in bats that do not yet echolocate. Its frequency is lower (46 kHz) and the corresponding threshold minimum of cochlear microphonic potentials is broader than in adults. Long-lasting ringing of the cochlear microphonic potential after tone stimulus offset that characterizes the adult auditory response close to CF2 is absent in newborns. In the course of the first 5 postnatal weeks, there is a concomitant upward shift of CF2 and the frequency of cochlear threshold minima. Up to the end of the third postnatal week, sensitivity of auditory threshold minima and the Q value of the cochlear resonance increase at a fast rate. Between 2 and 4 wk of age, two cochlear microphonic threshold minima are found consistently in the CF2 range that differ in their level-dependent dynamic growth behavior and are 1.5-5.7 kHz apart from each other. In older animals, there is a single minimum that approaches adult tuning in its sharpness. The data provide evidence to show that during maturation of the cochlea, the frequency and the sensitivity of the threshold minimum associated with CF2 increases and that these increases are associated with the fusion of two resonances that are partly dissociated in developing animals.

Acoustic Stimulation↗

PubMed2003

Development of echolocation calls in the mustached bat, Pteronotus parnellii.

Adult mustached bats employ Doppler-sensitive sonar to hunt fluttering prey insects in acoustically cluttered habitats. The echolocation call consists of 4-5 harmonics, each composed of a long constant frequency (CF) component flanked by brief frequency modulations (FM). The 2nd harmonic CF component (CF2) at 61 kHz is the most intense, and analyzed by an exceptionally sharply tuned auditory system. The maturation of echolocation calls and the development of Doppler-shift compensation was studied in Cuba where large maternity colonies are found in hot caves. In the 1st postnatal week, infant bats did not echolocate spontaneously but could be induced to vocalize CF-FM signals by passive body motion. The CF2 frequency emitted by the smallest specimens was at 48 kHz (i.e., 0.4 octaves lower than the adult signal). CF-FM signals were spontaneously produced in the 2nd postnatal week at a CF2 frequency of 52 kHz. The CF2 frequencies of induced and spontaneous calls shifted upward to reach a value of 60.5 kHz in the 5th postnatal week. Standard deviations of CF2 frequency were large (up to +/-1.5 kHz) in the youngest bats and dropped to values of +/-250 Hz at the end of the 3rd postnatal week. Some individuals in the 4th and 5th postnatal weeks emitted with adultlike frequency precision of about +/-100 Hz. In the youngest bats, the 1st harmonic CF component (CF1) was up to 22 dB stronger than CF2. Adultlike relative levels of CF1 (-28 dB relative to CF2) were reached in the 5th postnatal week. In spontaneously emitted CF-FM calls, the duration of the CF2 component gradually increased with age from 5 ms to maximum values of 18 ms. Durations of the CF2 component in induced calls averaged 7 +/- 2.6 ms in the 1st postnatal week and 8.2 +/- 1.5 ms in the 5th postnatal week. There were no age-related changes in duration of the terminal FM sweep (3 +/- 0.4 ms) in both induced and spontaneous calls. The magnitude of the terminal FM sweep in spontaneous calls was not correlated with age (mean 13.5 +/- 2 kHz). Values for induced calls slightly increased with age from 11 +/- 2 to 13 +/- 2 kHz. The emission rate of induced CF-FM signals increased with age from values of 2.5 +/- 2 to 17 +/- 5 pulses/s. Values for spontaneously emitted calls were 4.4 +/- 3 and 9 +/- 4.5 pulses/s, respectively. Doppler-shift compensation, as tested in the pendulum task, emerged during the 4th postnatal week in young bats that were capable of very brief active flights, but before the time of active foraging outside the cave.

Acoustic Stimulation↗

PubMed2002

[Long-term outcome of AV node modulation in 387 consecutive patients with AV nodal reentrant tachycardia].

UNLABELLED: Aim of this study was to assess the long-term results of AV-node modulation in patients with AV nodal reetrant tachycardia. METHODS: From December 1991 until September 1999, AV node modulation (ablation of the fast pathway or ablation/modification of the slow pathway) was performed in 387 consecutive patients with clinically apparent AV nodal reentrant tachycardia. Follow-up data was available in 95% of patients with a mean of 41 +/- 26 months after ablation. RESULTS: Acute success rate was 97%. During long-term follow-up recurrence rate was 7.4% without any difference between fast and slow pathway ablation. Recurrence occurred in 23% of patients with persistent dual AV node physiology after ablation (modification of the slow pathway) in contrast to 3% without dual AV node physiology (ablation of the slow pathway) (p = 0.002). The presence of a dual AV node physiology after slow pathway modulation was the only predictor of recurrence during long-term follow-up. The complication rate was 5.7%. The incidence of complete heart block was 1% without any difference between fast and slow pathway ablation. CONCLUSIONS: Catheter modulation of the AV node for the treatment of AV nodal reentrant tachycardia is effective and safe. During long-term follow-up, the recurrence rate was low. Modulation of the slow pathway is associated with a significantly higher recurrence rate than ablation of the slow pathway.

Adult↗

PubMed2001

[2 year follow-up of 321 patients with an implantable cardioverter/defibrillator: comparison of patients with and without atrial fibrillation].

UNLABELLED: Atrial fibrillation is the most common cause of inappropriate therapy deliveries by implantable cardioverter/defibrillators (ICD). However, the importance of atrial fibrillation for the induction of ventricular arrhythmias and for the prognosis is controversial. We studied 321 ICD patients (pts) over the median follow-up of 25 months. In 92 pts, atrial fibrillation was found to be the underlying rhythm (in 49 pts chronic, in 43 pts paroxysmal), in 229 pts sinus rhythm. Pts with atrial fibrillation were older (67 +/- 9 vs. 63 +/- 9 years, p = 0.001) and were considered to suffer more often from a valvular (14 vs. 4%, p = 0.004) or a dilative cardiomyopathy (29 vs. 19%, p = 0.04). Both groups were similar regarding other baseline characteristics like gender, left ventricular ejection fraction, hypertension, diabetes and in the ICD system (single chamber, dual chamber) used. Pts with atrial fibrillation experienced more appropriate (ventricular fibrillation: 0.33 vs. 0.2/month, p = 0.0049, ventricular tachycardias: 0.05 vs 0/month, p = 0.0033) as well as inappropriate (34 vs. 8%, p < 0.001) therapy deliveries by the ICD. Pts with atrial fibrillation were found to suffer twice as much from a progression of their heart failure (43% vs. 22%, p < 0.001). After multivariate analysis, atrial fibrillation was significantly associated with progressive pump-failure mortality (relative risk (RR) 3.12, confidence interval (CI) 1.30 to 7.48, p = 0.01). There was no difference in the incidence of ICD therapies and mortality rates between the pts with chronic and paroxysmal atrial fibrillation. CONCLUSION: The presence of atrial fibrillation in ICD patients is associated with a progression of heart failure and therefore is an unfavorable factor for pump-failure death. Also, atrial fibrillation is a marker for greater possibility to experience more appropriate as well as inappropriate therapy deliveries by the ICD.

Aged↗

PubMed2001

Functional organization of the dorsal cochlear nucleus of the horseshoe bat (Rhinolophus rouxi) studied by GABA and glycine immunocytochemistry and electron microscopy.

Unique among mammals, the dorsal cochlear nucleus (DCN) of horseshoe bats consists of two functionally and anatomically distinct subdivisions: a laminated ventral portion that processes the frequency range below the constant frequency (CF) component of the echolocation signal and a nonlaminated dorsal portion that is specialized for processing the CF-signal range (76 kHz and higher). Using conventional transmission electron microscopy and postembedding immunocytochemistry for the inhibitory neurotransmitters GABA and glycine on semithin-alternating sections, we present further evidence that the ventral laminated subdivision of DCN conserves the main elements of microcircuitry and GABA/glycine labeling patterns typical for the mammalian DCN: (i) the main cell types and synaptic inventory of the granule cell/cartwheel cell system of the superficial layers are present as well as (ii) the tuberculoventral cell system of the deep layers. The nonlaminated dorsal subdivision lacks the granule cell/cartwheel cell system and is composed of a mixture of fusiform projection neurons with tuberculoventral cell analogues. Thus the inhibitory tuberculoventral system known to play an important role in temporal and spectral processing in VCN is conserved throughout the DCN of horseshoe bats, whereas functional components of cerebellar-like circuits are reduced in a specialized region that processes the dominant biosonar component.

Animals↗

PubMed2001

Laminar analysis of inhibition in the gerbil primary auditory cortex.

Physiological and immunocytochemical evidence indicates a layer-dependent organization of inhibitory circuits in the neocortex. To investigate the contribution of GABAergic inhibition to frequency tuning in the different cortical layers, we recorded single and multiple units in near-radial penetrations before and during iontophoretic application of the GABA(A)-receptor antagonist bicuculline in the auditory cortex of the lightly anesthetized gerbil. Bicuculline generally increased the spontaneous rate and enhanced and prolonged onset activity. Application of bicuculline often resulted in a shift of best frequency and a decrease of threshold (5.5 dB). A broadening of the frequency tuning evident by lower Q40dB values was observed in 63% of the units. In units with multipeaked tuning curves or clearly separated response areas, bicuculline application removed the inhibitory regions and created single-peaked tuning curves. The influence of bicuculline on the receptive field size was not significantly layer-specific but tended to be most pronounced in layers V and VI. In layer VI, we frequently found "silent" neurons that responded to sound only when GABAergic inhibition was antagonized. From the analysis of postembedding GABA immunocytochemistry, the proportion of GABAergic neurons was found to be maximal in layers I and V, and the number of GABAergic perisomatic puncta (axon terminals) on cell somata peaked in layer V.

Animals↗

PubMed2001

Cellular and subcellular distribution of AMPA-type glutamate receptor subunits and metabotropic glutamate receptor 1alpha in the cochlear nucleus of the horseshoe bat (Rhinolophus rouxi).

Ionotropic alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) selective glutamate receptors (GluRs) are the main mediators of fast excitatory neurotransmission and composed of a variable combination of four different subunits (GluR1-4). The metabotropic glutamate receptor 1alpha (mGluR1alpha) is involved in plastic synaptic events. Since horseshoe bats strongly depend on temporal cues for acoustic imaging by echolocation and exhibit prominent species specific specializations of the cochlear nucleus (CN), the subunit distribution of AMPA selective GluRs and the distribution of mGluR1alpha was studied at the light and electron microscopic level with preembedding immunocytochemistry. Immunoreactivity to GluR1 was low throughout the CN. All types of projection neurons of the ventral CN expressed distinct GluR2/3 and GluR4 immunoreactivity with GluR4-labeling especially prominent in multipolar and octopus cell-like neurons of the posteroventral CN. The AMPA and metabotropic receptor inventory of the laminated ventral subdivision of the dorsal CN (DCNv) agreed with that reported in other mammals, whereas the specialized dorsal non-laminated subdivision of DCN (DCNd) lacked the prominent labeling for GluR2/3 and mGluR1alpha that characterizes cartwheel cells of DCNv. Distinct GluR2/3 and GluR4 immunoreactivity combined with low expression of mGluR1alpha immunoreactivity was characteristic for fusiform cells of DCNv and DCNd. Tuberculoventral cells of both the deep DCNv and the DCNd exhibited light to moderate GluR2/3 and GluR4 immunoreactivity. The staining patterns in DCNd thus indicate a loss of cerebellar-like microcircuits and a conservation of frequency specific circuitry of the deep and fusiform cell layers of the mammalian DCN.

Animals↗

PubMed2001

Assessment of pain by parents in young children following surgery.

BACKGROUND: We asked parents to assess pain in young children following surgery. METHODS: Assessments were carried out by both parents and an independent assessor using a behavioural observational scale. RESULTS: Forms were returned from the parents of 42 children aged 1-5 years. There were 123 joint assessments and there was a strong correlation between the scores by the observer and the parents (r2=0.84). Twenty-nine children experienced pain following discharge from hospital. CONCLUSION: Our findings suggest that parents can assess pain in young children following surgery. The management of pain following discharge from hospital can be improved.

Adult↗

PubMed2000

Consequences of outer hair cell damage for otoacoustic emissions and audio-vocal feedback in the mustached bat.

The cochlea of the mustached bat is adapted to process ultrasonic echolocation signals. To assess the involvement of active sound amplification by outer hair cells in high-frequency hearing and in audio-vocal interaction, selective hair cell damage was induced by the antibiotic Amikacin. Amikacin preferentially damaged the first row of outer hair cells in the basal cochlear turn. The cochlear regions coding for the second-harmonic constant-frequency component of the echolocation call (CF2) at 61 kHz and for frequencies between 75 and 100 kHz were the most affected. This was reflected in an increase of mechanical thresholds obtained by measuring distortion-product otoacoustic emissions. During initial periods of minor hair cell damage, when thresholds had deteriorated by less than 40 dB, a sharp, mechanical, cochlear resonance that is responsible for enhanced tuning to 61 kHz was still measurable as a stimulus-frequency otoacoustic emission and its frequency decreased by 350 Hz. The persistence of the resonance suggests that passive structures like the tectorial or basilar membrane are important for generation of the resonance. Behaviorally, the bats reacted to the change in cochlear micromechanics with a decrease of their CF2 frequency by 360 Hz. After larger hair cell damage, when the cochlear resonance had disappeared, the bats vocalized only sparsely and the CF2 frequency increased by up to 2 kHz, which may correspond to a state without audiovocal feedback. This indicates that audio-vocal feedback in the nondamaged animal works to lower the call frequency.

Animals↗

PubMed1998

Postnatal development of GABA- and glycine-like immunoreactivity in the cochlear nucleus of the Mongolian gerbil (Meriones unguiculatus).

The maturation of the morphological substrate for inhibitory interactions was investigated in the cochlear nucleus of the gerbil with immunocytochemistry for gamma aminobutyric acid (GABA) and glycine on alternating vibratome sections. The patterns of immunostaining obtained with both antibodies in the adult closely conformed to the general mammalian scheme. Qualitative analyses revealed an age-related increase in staining intensity and in the relative numbers of immunolabelled cells after birth up to the age of 3-4 weeks. As early as birth and in all subdivisions of the cochlear nucleus, a few labelled cells and puncta in the sections were stained either with the GABA or the glycine antibody. Immunoreactive puncta and cells were, however, far less abundant than in the adult, and the staining intensity of cells was only weak. The most strikingly GABA-immunolabelled cells at birth were the Golgi cells of the granule-cell domains. The numbers of weakly GABA- and glycine-immunostained cells of the dorsal cochlear nucleus clearly increased between birth and the third postnatal week. At approximately the onset of hearing (postnatal day 12-14), some cells of the dorsal cochlear nucleus and small cells of the ventral cochlear nucleus gained adult-like GABA-staining properties. Almost adult-like labelling intensity was observed in glycine-immunoreactive cells of the deep dorsal cochlear nucleus and in some small cells of the ventral cochlear nucleus. Puncta staining to both antibodies appeared adult-like throughout the cochlear nucleus. About 2 weeks after the onset of hearing (at the latest), adult-like staining of all subsets of immunoreactive cells occurred throughout the cochlear nucleus in all specimens.

Animals↗

PubMed1997

Development of the organ of Corti in horseshoe bats: scanning and transmission electron microscopy.

The late prenatal and early postnatal development of the organ of Corti were studied in the horseshoe bat (Rhinolophus rouxi) by using scanning and transmission electron microscopy. Arrangements and dimensions of stereocilia bundles, together with their contacts with the tectorial membrane, were found to be adult-like shortly before birth, and thus before the biological onset of hearing (3-5 days after birth). During the first postnatal week, there were baso-apical gradients in disappearing kinocilia on inner hair cells (IHC), microvillis of supporting cells, and marginal pillars. The lower basal cochlear turn was mature with respect to these regressing structures at 3 days after birth, the apical turn at 10 days after birth. At birth, cytodifferentiation was found to be completed, and the tunnel of Corti and innermost spaces of Nuel had opened. The ultrastructure of IHCs was not markedly different from that at later ages. In outer hair cells (OHC), the adult-like regular arrangement of a single layer of subsurface cisternae and pillars was seen as soon as protrusions of supporting cells had withdrawn from the lateral wall of OHCs (basal turn at birth and throughout the cochlea 2 days after birth). Numerous efferent endings contacted the somata of IHCs up to the second postnatal week. Since the medial olivocochlear system is absent in horseshoe bats, the adult-like innervation pattern of OHCs was established at the biological onset of hearing. During the first 2 postnatal weeks, the cytoskeleton of pillar and Deiters cells, and the specialized Deiters cups developed. The organ of Corti appeared adult-like at 14 days, apart from the persistence of a reduced tympanic cover layer attached to the basilar membrane. Morphological data support physiological findings that the first broadly tuned auditory responses arise from the basal turn. The distinct low to high frequency gradient in development of sensitivity during the first 2 postnatal weeks of the horseshoe bat was not, however, matched by morphological gradients, and it would appear that the development of the cytoskeleton of supporting cells contributed to the establishment of tuning in the auditory fovea. Adult-like morphology of the organ of Corti coincided with the emergence of sharply tuned responses from the auditory fovea, but there was no clear-cut correlate for the shift in tuned foveal frequency representation that occurred during the following 3 weeks.

Animals↗

PubMed1997

The distribution of GABA and glycine immunostaining in the cochlear nucleus of the mustached bat (Pteronotus parnellii).

The distribution of neuronal elements immunoreactive for gamma-aminobutyric acid (GABA) and glycine in the cochlear nucleus of the mustached bat Pteronotus parnellii has been studied by means of the postembedding technique on serial semithin sections. Our goal has been to identify similarities and differences in the organization of putatively inhibitory circuits between a highly specialized echolocating bat and previously studied non-echolocating mammals. The results reveal a basically conserved pattern of putatively GABAergic and glycinergic elements in the bat cochlear nucleus, and subtle but distinct modifications in certain inhibitory circuits. As in other mammals, immunoreactive cells possibly representing local interneurons are most abundant in the dorsal cochlear nucleus. These include single-GABA-immunoreactive cells and double-labeled cells in the superficial layers and single-glycine-labeled cells in the deep layers. Coincident with the phylogenetic trend toward a reduced lamination of the dorsal cochlear nucleus in bats, there is a clear reduction in the numbers of local interneurons of the superficial layer. In contrast, the tuberculoventral system of the deep layer appears hypertrophied. As in other mammals, the ventral cochlear nucleus contains a few large single-glycine-immunoreactive cells and scattered double-labeled cells. Immunoreactive puncta are abundant throughout the cochlear nucleus complex with no trends indicating a differential strength of inhibitory inputs to regions representing the various harmonics of the echolocating signal.

Animals↗

PubMed1997

The columnar region of the ventral nucleus of the lateral lemniscus in the big brown bat (Eptesicus fuscus): synaptic arrangements and structural correlates of feedforward inhibitory function.

Neurons of the columnar region of the ventral nucleus of the lateral lemniscus of Eptesicus fuscus respond with high-precision constant-latency responses to sound onsets and possess remarkably broad tuning. To study the synaptic basis for this specialized monaural auditory processing and to elucidate the excitatory or inhibitory nature of the input and output circuitry, we have used classical transmission electron microscopy, and postembedding immunocytochemistry for gamma aminobutyric acid (GABA) and glycine on serial semithin sections. The dominant putatively excitatory perisomatic input is provided by large calyx-like terminals that possess round synaptic vesicles and asymmetric synaptic contacts. Additionally, calyces contact the dendrites of neighboring neurons. Putatively inhibitory small boutons possess pleomorphic or flattened synaptic vesicles and symmetrical contacts and are sparsely distributed on somata and dendrites. Almost all neurons are glycine-immunoreactive. There is a moderate amount of glycine-immunoreactive puncta; GABA-immunoreactive puncta are rare. This suggests that (1) there is a fast robust excitatory synaptic input via calyx-like perisomatic endings, (2) calyx-like endings distribute frequency-specific excitatory input across isofrequency sheets by virtue of parallel synapses to somata and adjacent dendrites, and thus, dendritic integration may contribute to the broadening of frequency tuning, (3) the columnar region forms an inhibitory glycinergic feedforward relay in the ascending auditory pathway, a relay that is probably involved in creating filters for time-varying signals.

Afferent Pathways↗

PubMed1997

The 9-O-acetylated disialosyl carbohydrate sequence of CDw60 is a marker on activated human B lymphocytes.

Gangliosides with a terminal 9-O-acetylated disialosyl group (CDw60 structures) show a restricted surface expression on human leukocytes. Hithereto, they have only been detected on subpopulations of human T lymphocytes. Using the defined CDw60 antibody UM4D4 and two new antibodies with preferential CDw60 activities, F6 and Z17, we demonstrate for the first time that CDw60 is an activation marker on human B lymphocytes. In vitro phorbol ester-stimulated human peripheral blood B lymphocytes as well as in vivo activated tonsillar B lymphocytes became CDw60 positive. CDw60 expression of these cells exceeds that of resting and activated T-lymphocytes.

Acetylation↗

PubMed1997

The postnatal development of F-actin in tension fibroblasts of the spiral ligament of the gerbil cochlea.

The tension fibroblasts of the spiral ligament of the mammalian cochlea are thought to create radial tension on the basilar membrane. Their postnatal development was investigated in the gerbil (Meriones unguiculatus) with confocal fluorescence microscopy using phallotoxin as a specific marker for F-actin. In the adult cochlea, tension fibroblasts were restricted to the basal cochlear turn and were arranged in 2-4 rows in the marginal region of the spiral ligament. They contained intensely stained parallel bundles of F-actin. In upper cochlear turns, the marginal region of the spiral ligament was occupied by sparsely distributed, unobtrusively labeled fibrocytes, the bone lining cells. The spiral ligament of young postnatal stages (newborn--6 days after birth (DAB)) lacked F-actin labeling patterns that are characteristic for tension fibroblasts in the adult. Rather, the whole inner surface of the otic capsule throughout all cochlear turns was outlined by cell layers with distinct but diffuse cytoplasmic F-actin label. These cells may represent perichondrial fibrocytes. Around 9 DAB, the perichondrium revealed changes in morphology and F-actin patterns that indicate a further differentiation into tension fibroblasts (basal turn) or bone lining cells (more apical turns). At 12 DAB, around onset of hearing, adult-like bone lining cells were found in the marginal regions of the spiral ligament of upper cochlear turns. In the basal turn, tension fibroblasts were present, but their F-actin cytoskeleton was not fully developed. During the following days, F-actin label increased in tension fibroblasts and reached adult-like configuration at 17 DAB, coinciding with mature hearing characteristics. The role of tension fibroblasts in development of hearing characteristics is discussed.

Actins↗

PubMed1996

The early postnatal development of F-actin patterns in the organ of Corti of the gerbil (Meriones unguiculatus) and the horseshoe bat (Rhinolophus rouxi).

The arrangements of F-actin in hair cells and non-sensory cells were studied in paraformaldehyde-fixed cochleae of horseshoe bats and gerbils in several postnatal stages and in the adult. Phallotoxin-labeled midmodiolar cryostat sections of the organ of Corti were analyzed with confocal fluorescence microscopy. In both species, the arrangement of F-actin in the adult organ of Corti was essentially similar to that described in other mammals; however, both species showed their own species-typical specializations in staining of the Deiters cells. In the gerbil, a distinct baso-apical gradient in morphology and staining properties was found in the upper compartment of the Deiters cells. In the bat, F-actin label within the Deiters cups was most pronounced in the basal cochlear turn and less abundant in the apical turns. During the first postnatal week, the sensory epithelium of the gerbil lacked the tunnel of Corti and the spaces of Nuel. Only the reticular lamina and the surface of the greater epithelial ridge were intensely labeled for F-actin. At 9 days after birth (DAB), when the tunnel of Corti and the inner spiral sulcus were formed, the footplates of Deiters and pillar cells and the apices of pillar cells began to show intense F-actin label. At 12 DAB, corresponding to onset of hearing, F-actin staining was found throughout the supporting cell bodies, but was less intense than in the adult. The specialized upper compartment of the Deiters cells differentiated around 15-20 DAB. In the neonate bat, gross-morphology of the organ of Corti was almost adult-like, but only the reticular lamina and the head- and footplates of pillar cells showed intense F-actin staining. The F-actin cytoskeleton of the Deiters cells bodies was poorly developed. At the onset of hearing (between 3rd and 5th DAB), supporting cells showed only a slight increase of F-actin mainly at mechanically important cell regions, namely the Deiters cups, the contact zone of pillar headplates and the footplates of supporting cells. The most intense increase of F-actin occurred between onset of hearing and 16 DAB. At 16 DAB, the F-actin distribution within the supporting cells was similar to the adult. In both species, there were no clear baso-apical gradients in development of F-actin patterns. It is proposed that F-actin insertion in supporting cells after the onset of hearing contributes to maturation of cochlear function.

Actins↗