摘要:

Endolymphatic sac specimens from human embryos, ranging in age from 8 to 20 weeks, were examined in order to get a good understanding of the embryological development. The gross development can be separated into three phases, with the first phase terminating around week 10, the second phase between weeks 11 and 15–16 and the third phase lasting to week 20. While presenting as an immature oval appendage emanating from the vestibule in the first phase, the sac then develops into its more mature shape with crypts and folds within the epithelial lining. The third period is characterized by splitting up of the lumen into separate tubules. The epithelial cells differentiate particularly during the second and third phases with light- and dark-staining cells as well as granulated cells. It is evident that the development of the endolymphatic sac is not finished by week 20, even though it has attained many of its adult characteristic

ISSN:0301-1569    

DOI:10.1159/000276189

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

Hyaluronan (HA) 0.5, 1, 1.9 and 4% was instilled into the round window niche in mice. Six hours after the 1.9% HA and 4, 6 and 8 h after the 4% HA deposition there was a significant increase in the proportion of granule-containing light epithelial cells in the endolymphatic sac. This indicated an increase in secretory activity. This activity could be a response to lowered intralabyrinthine pressure due to the osmotic capacity of HA. Secretion of high molecular substances can serve to keep the sac lumen patent and/or to regulate labyrinthine volume and pressure.

ISSN:0301-1569    

DOI:10.1159/000276190

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

The rat is an altricial animal and is thus a useful model for the study of auditory development. The endocochlear potential (EP) undergoes a rapid increase in magnitude from the end of the 1st week to the beginning of the 3rd postnatal week. The purpose of this study was to examine the ultrastructure of the developing stria vascularis in the rat pup in order to correlate functional changes with structural alterations. Rat pups of various ages underwent EP measurement under Rompun anesthesia. The cochleas were rapidly removed under deep pentobarbital anesthesia. The tissues were fixed in 2.5% glutaraldehyde and postfixed in 1.5% osmium tetroxide. Thin sections were viewed and photographed using a Hitachi H7000 transmission electron microscope. A series of distinct developmental changes were observed. Intermediate and basal cells became more distinct from one another, and basal cells became more elongated. Marginal cells underwent progressive development of basolateral infoldings. These cyto-logic changes may signal the development of ion transport mechanisms necessary for EP development.

ISSN:0301-1569    

DOI:10.1159/000276191

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

The cytosolic calcium concentration ([Ca2+]i) of the isolated outer hair cell of the guinea pig was measured using fluorescence imaging microscopy and the effects of efferent neuroregulators such as acetylcholine, ATP, GABA, substance P, enkephalin, calcitonin gene-related peptide, serotonin, dopamine, norepinephrine, and gluta-mate were investigated. Among the drugs tested only ATP induced an elevation of the [Ca2+]i of the outer hair cell. In the resting condition, [Ca2+]i averaged 104.5 ± 31.1 nM(n = 27), while 100 µM ATP significantly increased [Ca2+]i to 146.3 ± 43.5 nM (n = 19). Superfusion with Ca2+-free solution (pCa = 7.5) abolished the increase in [Ca2+]i induced by ATP, suggesting that ATP causes an entry of external Ca2+. The relevance of [Ca2+]i to the inhibitory actions of efferent neuroregulators is discuss

ISSN:0301-1569    

DOI:10.1159/000276192

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

Vestibular hair cells were isolated from the macula utriculi, macula sacculi and crista ampullaris of the guinea pig, using enyzmatic and mechanical techniques. The cells could be classified into two types: flask-shaped ones with a neck and rod- or round-shaped ones without a neck. The flask-shaped cells were thought to be type I cells, the rod-shaped cells type II cells, while the round-shaped cells could have been type I or type II cells. The intracellular free calcium ion concentrations ([Ca2+]i) of these cells were determined using the Ca2+-sensitive dye Fura-2 and digital imaging miroscopy. In the resting state, [Ca2+]i in the nucleus and cuticular plate was variable in both types of cells. The 150 mMKCl stimulation, which might induce a depolarization, resulted in a temporary increase in [Ca2+]i in both types of cells. In the presence of 1 µm ionomycin, there was an irreversible increase in [Ca2+]i in both types of cells. These observations aid in elucidating vestibular function

ISSN:0301-1569    

DOI:10.1159/000276193

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

The presence of carbohydrates in the glycocalyx of the vestibular end organs of the guinea pig was investigated at the ultrastructural level using lectin-gold solutions. The glycocalyx of both the sensory and the supporting cells has variable sugar components. The glycocalyx of the sensory cells including the ciliary interconnections contains N-acetyl-glucosamine, galactose and mannose. In contrast, the glycocalyx of the supporting cells had a lower amount of N-acetylglucosamine. The ciliary interconnections, which have been considered to be a part of the glycocalyx, have larger amounts of galactose and mannose than the surface glycocalyx. These findings indicate that the sugar components may be closely related to the functional significance of the inner-ear glycocalyx and that the functional properties of the glycocalyx may differ between the sensory and the supporting cells of the vestibular end organs.

ISSN:0301-1569    

DOI:10.1159/000276194

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

The effects of topical otic preparations (Cortisporin®, Coly-Mycin®, Aristocort®, and Bestron®) upon the permeability of the round window membrane (RWM) in chinchillas were investigated. Using K+-selective microelectrodes, the concentration of tetraethylammonium (TEA) ions was measured. Changes in the thickness of the RWM were measured using light microscopy. The RWM permeability was reduced significantly in Cortisporin-and Coly-Mycin-treated ears. Moreover, these two drugs resulted in a marked thickening of the RWM. In contrast, Aristocort or Bestron resulted in no alteration of the RWM permeabil

ISSN:0301-1569    

DOI:10.1159/000276195

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

The relationship between the head size and the latency and amplitude of the auditory brainstem response (ABR) was investigated in 60 normal-hearing adults (30 males and 30 females). We found a strong positive correlation between the latency of ABR waves and the head size and a strong negative correlation surfaced between the ABR amplitude and head size. These results indicate that the head size is one of the most important factors influencing the waveform of the ABR.

ISSN:0301-1569    

DOI:10.1159/000276196

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

Variations in spinal motoneuron excitability, tested by the monosynaptic H reflex of the soleus muscle, were studied in man in relation to angular acceleration of the body in a damped rotating chair. Clockwise and anticlockwise rotation produced similar changes on the same spinal motoneurons, consisting of a first clear-cut facilitatory phase starting at 0.4 degrees of rotation (corresponding to 156 ms) with a peak between 10 and 30 degrees, followed by a second excitatory phase between 50 and 100 degrees; then, the amplitude of the H reflex progressively recovered to its control value. Both facilitatory phases showed a significant decrease by reducing the angular velocity and acceleration. Control experiments ruled out that both the startle reaction of the subject and variations in the somatosensory input during rotation could be responsible for generating the facilitatory effects on the H reflex. The mean value of the voluntary reaction to turning sensation was 1.1 degrees, corresponding to about 335 ms. It is concluded that the changes described in motoneuron excitability could represent a vestibulospinal reflex response originating from the horizontal semicircular canals.

ISSN:0301-1569    

DOI:10.1159/000276197

出版商:S. Karger AG    

年代:1991

数据来源: Karger

摘要:

To investigate whether automobile drivers with the clinical features of sleep apnea syndrome (SAS) perform worse than controls in a simulated long-term test drive, and to see if their driving improves after uvulopalatopharyngoplasty (UPPP), 15 male drivers with SAS, suffering from sleep spells whilst driving, and 10 matched controls without a history of SAS or hypersomnia at the wheel were tested in an advanced driving simulator. Brake reaction time, lateral position deviation and off-road episodes were measured during a 90-min rural drive at twilight conditions. The clinical evaluation was made by a questionnaire scoring symptoms of snoring, sleep disturbances and diurnal sleepiness before and after surgery. Before UPPP the patient group showed impaired performance in all three effect measures compared to controls. UPPP resulted in improved reaction time performance (average mean improvement: 0.5 s, average 90th percentile improvement 0.8 s). Furthermore, 12 of the 15 patients reported a marked improvement regarding sleepiness whilst driving. For these clinically successful cases the number of off-road episodes decreased substantially. We conclude that most patients improve their long-term driving performance as a result of UPPP.

ISSN:0301-1569    

DOI:10.1159/000276198

出版商:S. Karger AG    

年代:1991

数据来源: Karger