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At least 253 records · Page 14Linked to original sources
PubMed1976

Axonal labyrinths in the rat spinal cord: a consequence of degenerative atrophy.

Transection, crush or local colchicine treatment of a peripheral nerve induces degenerative atrophy of central terminals of primary sensory neurons in the Rolando substance of the rat spinal cord. In addition to osmiophilic alterations that occur in the course of degenerative processes in general, degenerative atrophy is characterized by the appearance of spectacular labyrinthine formations. Electron-microscopic analysis reveals that these consist of flattened axonal profiles. Axonal labyrinths are interpreted as signs of futile regenerative efforts of axon terminals undergoining degenerative atrophy. Labyrinths disappear from the Rolando substance several months after peripheral nerve injury, when degenerative atrophy of the central terminal is replaced by regenerative proliferation.

Animals↗
PubMed2000

[Vertical vestibulo-ocular interaction in unilateral labyrinth lesion (communication II)].

Vertical vestibuloocular reflex (VVOR) suppression was studied in 25 patients with unilateral labyrinthine disorders and 22 healthy individuals. The method of the suppression investigation was based on stimulation of the internal semicircular channels of the labyrinth by active sagittal nodding with glance fixation of the object moving with the head. VVOR suppression by glance reflex in patients with unilateral labyrinthine lesion is characterized by reduced reflex suppression effectiveness, especially on the side of the affected labyrinth, via a significant VVOR phase shift down.

Adolescent↗
PubMed1975

[Possible functional properties of the labyrinth in Brachiosaurus brancai].

The dimensions of the semicircular canals and the respective ampullae of a complete labyrinth caste of Brachiosaurus Brancai were determined. Using the equation of motion and the dimensions of the semicircular canals the behaviour of the endolymph displacement of the Brachiosaurus labyrinth was calculated. The time constants of the system were found to be between the values 4 sec and 13 sec for T1 and 0.2 sec and 0.5 sec for T2. From these results it was concluded, that the head movements of the animal occurred in a range between 0.02 and 0.1 cps.

Animals↗
PubMedDate not supplied

Further contribution in the densitometric study of the labyrinthic capsule with special reference to the bottom of the internal auditory meatus.

The quantity of minerals in the labyrinthic capsule of the basal coil and of the separating wall facing the internal auditory meatus in different life periods was determined by the densitometric method. The quantity of minerals is reduced in the labyrinthic capsule and in the separating wall in spite of the bone apposition and increasing thickness of the separating wall.

Adolescent↗
PubMed2003

[The dosage of SDS when extracting membranous labyrinth proteins].

OBJECTIVE: To determine the appropriate dosage of SDS when extracting membranous labyrinth proteins. METHOD: The yield of proteins extracted with various amounts of SDS were determined by BCA method, and the components of the extracted proteins were analyzed by SDS-PAGE. RESULT: The amount of proteins extracted with 0.1% SDS is less than that with 0.23%, 1% or 2% SDS, meanwhile it shows less bands than the other and the corresponding bands are stained weaker. 0.23% SDS is less efficiently than 1% and 2% SDS in solubilizing proteins. There is no significant difference between 2% and 1% SDS in yield of proteins, while 2% SDS accompanies a higher ratio of detergent to protein. CONCLUSION: 1% SDS is solutions is relatively suitable for extracting membranous labyrinth proteins extensively while the ratio of detergent to protein is from 5 to 6.

Animals↗
PubMed2004

3-T imaging of the cochlear nerve and labyrinth in cochlear-implant candidates: 3D fast recovery fast spin-echo versus 3D constructive interference in the steady state techniques.

BACKGROUND AND PURPOSE: High-resolution imaging of the internal auditory canal and labyrinth at 1.5 T is often performed by using three-dimensional (3D) fast spin-echo or T2* techniques. We evaluated both techniques at 3 T in the preoperative assessment of patients being considered for cochlear implants. METHODS: Sagittal 3D fast recovery fast spin-echo (FRFSE) and 3D constructive interference in the steady state (CISS) images were acquired in eight patients at 3.0 T by using dual surface coils. Contrast-to-noise ratios (CNRs) for the intracanalicular nerve and CSF were measured in the internal auditory canal. Two neuroradiologists reviewed the images to determine whether the techniques provided images of diagnostic quality. RESULTS: CNRs for 3D CISS were twice those obtained with 3D FRFSE. Both techniques provided images of diagnostic quality, though spurious signal intensity loss at the apex of the superior semicircular canals was encountered on 3D FRFSE images in four of eight patients. CONCLUSION: Both 3D FRFSE and 3D CISS provide high-resolution images of the internal auditory canal and labyrinth at 3.0 T. We predict that the superior CNRs obtained with 3D CISS will prove advantageous as we move to smaller fields of view at higher field strength.

Artifacts↗
PubMed2006

[An in vitro investigation of the regulation mechanism to the blood-labyrinth barrier permeability of guinea pig inner ear].

OBJECTIVE: To investigate the regulation mechanism of the blood-labyrinth barrier permeability of guinea pig inner ear. METHOD: The cultured endothelial cell was derived from the stria vascularis from guinea pig inner ear. We exposed guinea pig inner ear capillary endothelial cell monolayers to substances known to increase or decrease cyclic AMP and measured their effect on endothelial permeability to albumin and Evan's blue and endothelial cell cyclic AMP and F-actin concentrations. RESULT: Cholera toxin (CT) led to a remarkable increase in cyclic AMP concentration and a marked reduction in F-actin concentration which was associated with remarkable reduction in albumin and Evan's blue transfer across endothelial monolayers; In contrast, katlex led to an obvious reduction in cyclic AMP concentration and a marked increase in F-actin concentration which was associated with obvious increase in albumin and Evan's blue transfer across endothelial monolayers. CONCLUSION: The results indicated that cyclic AMP is an important determinant of the blood-labyrinth barrier in vitro. The barrier function changes are probably associated with apparent endothelial shape changes and qualitative and quantitative changes in F-actin.

Actins↗
PubMed1991

[Visual illusions during the electrical stimulation of the labyrinth].

Transcutaneous electrical stimulation of the labyrinth induced apparent motion of a stationary light source in darkness in normal subjects. This effect is similar to the oculogyric illusion induced by rotatory vestibular stimulation. Monaural anodal stimulation of the right labyrinth evoked apparent movement of the target to the left, whereas cathodal stimulation induced opposite illusion. The threshold current was 0.35-0.6 mA. Binaural bipolar stimuli induced illusory target motion directed to the side of the cathode, the threshold decreased 1.5-2.5 times. Binaural monopolar stimulation induced vertical apparent displacement of a target, the threshold being 1.4-3.0 mA. The amplitude and velocity of illusory target motion increased with current. The subject eyes began to move with much higher currents than those necessary for illusory sensation. It is therefore suggested that the visual illusion is related not to vestibulo-visual interaction but to vestibular effects on the spatial perception system.

Darkness↗
PubMedDate not supplied

[Topographic anatomy of the ethmoid labyrinth in x-ray computed tomography].

These last years the surgical treatment of inflammatory ethmoid disease has been completely modified, with new endoscopic conservative procedures. In a preoperative phase it is mandatory to provide optimal CT imaging of the ethmoid labyrinth, and for this purpose sections perpendicular and parallel to the nasofrontal duct axis are better than axial and coronal slices. The anatomy of the ethmoid is fairly complex; however certain constant anatomic landmarks allow a systematic analysis of the ethmoid labyrinth: the unciform process, the bulla, the middle turbinate, the superior turbinate and their respective basal lamellae.

Ethmoid Sinus↗
PubMedDate not supplied

[Characteristics of the oculo-vestibulomotor interaction during experimental asymmetry of the labyrinth].

Eye and head coordination in response to trigger and predictive patterns of the gaze fixation reaction was investigated in 19 healthy men under normal conditions and during unilateral monopolar stimulation of the labyrinths. Transient changes in movement coordination and asymmetry of velocity and amplitude characteristics of oculomotor components which deteriorated regulation of search-information reflexes were detected. Changes in the regulation of eye and head movements in response to experimental asymmetry of labyrinths were followed by short-term visual symptoms of the scillopsia type. This was a result of changes of the gain coefficient in the system of ocular, vestibular and motor interaction. It is postulated that labyrinthine asymmetry is one of the mechanisms of sensory mismatch underlying somatomotor discoordination.

Adult↗
PubMed1989

[A comparative study of the main components of the nucleolus in different populations of rat trophoblast cells during differentiation. I. The nucleoli of the trophoblast cells in the labyrinth section of the placenta].

The nucleolus undergoes some steps of structural transformation during differentiation of the labyrinth trophoblast cells. Primarily (on day 13 of gestation) the nucleolar components become rather disjoined. The nucleolus is composed of a loose net of strands of granulofibrillar and dense fibrillar components bearing fibrillar centers (FCs). Strands are separated by large lacunae. This rare-occurring type of nucleoli is replaced on the next (14th) day by the nucleolonemal type and later--by the compact nucleolar type. FCs with dense fibrillar component strands become extended into the masses of granulofibrillar component. Such transformations of nucleolar structure seem to be an expression of a fast-proceeding differentiation of the labyrinth trophoblast cells.

Animals↗
PubMedDate not supplied

[Plasticity of the behavior of Myrmica rubra ants during learning in a multi-alternative symmetric labyrinth].

The ability was studied of Myrmica rubra ants to change the habit of passing through a multialternative symmetric labyrinth at motivation of the care for posterity. In exams the location of reinforcement was changed: in the first exam the progeny was carried from both aim places to those symmetric to them relatively to labyrinth cross axis; in the second exam the reinforcement was left on one aim place non-preferred during learning. The first exam was passed by 62.5% of ants, the second--by 87.5%. In the first exam such parameters were worse as the first correct decision, the mean number of movements in the cycle, the total number of correct cycles. At elaboration of new motor habits and increase and inversion were observed of the initial spatial-motor asymmetry. Individual variations in ants behaviour increased. The ants who failed to solve the task, showed pronounced signs of preneurotic state. The obtained results testify to a high plasticity of ants behaviour and their ability to modify their activity according to changes of experimental situation.

Animals↗
PubMed1989

[Characteristics of processes of excitation and inhibition of monosynaptic spinal reflexes after removal of the labyrinth].

Some electrophysiological changes were found within 1.0-1.5 hrs after removal of the labyrinth. The amplitude of extensor monosynaptic reflexes decreased. Recurrent inhibition weakened, amplitude of flexor monosynaptic reflexes increased, presynaptic inhibition decreased and recurrent inhibition was reinforced. Functional role of spontaneous influences of the labyrinth removal involves not only the reinforcement of extensor motoneurons but an increasing and stabilizing of reciprocal inhibition, restriction and stabilizing of reciprocal inhibition, restriction of information inflow and amplifying of differences of excitatory levels between active and passive reflex pathways.

Action Potentials↗
PubMedDate not supplied

[Physiologic reactions to electric stimulation of the labyrinth].

Physiological responses to electric stimulation of the skin projections of labyrinths on the outer ear were investigated. The experiments were carried out on 56 test subjects using electric current in the range of 20 microA to 1.5 mA with the frequency 0.2-0.5 Hz. Thresholds for the emergence of autonomic, somatomotor and sensory manifestations were detected. It was found that autonomic reactions may develop independently of somatomotor responses. It is postulated that autonomic, motor and sensory reactions to electric stimulation of labyrinths constitute a combined response which is of afferent vestibular and skin origin.

Adolescent↗
PubMedDate not supplied

[The volume of reinforcement and the structure of rat behavior in a radial labyrinth].

In rats choice reaction was elaborated in 12 passages radial labyrinth with different volumes of food only in six of twelve passages. Then the conditions were modified: the first group of rats in the beginning of the experiment was placed to another labyrinth sector, and in the second group the food volume was changed in passages. In new situations in animals of both groups the reaction efficiency temporarily decreased, simultaneously the correction of behaviour structure took place. The character of behavioural tactics (tendencies to visit passages with larger food volume at the beginning of the experiment, spatial-motor asymmetry etc.) is described in dynamics of adaptation to new conditions. Factors determining the rats behaviour structure are discussed.

Animals↗
PubMed1988

[Ultrastructural features of the nucleus and cytoplasm of rat trophoblast cells of the connective zone of the placenta and labyrinth].

Ultrastructural organization of the rat trophoblast cells in the connective zone of placenta and labyrinth was investigated on the 12-14th days of gestation. A clear distinction was revealed in the cytoplasm ultrastructure of two cell subpopulations within the connective zone of placenta, i.e. glycogen and trophospongium cells. The former display a well defined network of long thin channels of granular endoplasmic reticulum situated mainly around the glycogen clusters. On the contrary, the latter are rich in the smooth endoplasmic reticulum but lacking glycogen accumulation. Differences in the nucleolar ultrastructure in these two cell subpopulations are not very considerable. A characteristic feature of glycogen cells is the presence of numerous round or oval small-fibrillar nucleolus-like bodies with the diameter of granules 20 nm. The trophoblast cells of the labyrinth are heavily laden with polysomes, which sometimes attach to short channels of the granular endoplasmic reticulum. Not often there occur short profiles of the agranular endoplasmic reticulum. Nucleolus-like bodies are found in all the cell types examined. This means that the nucleolus-like bodies may arise not only on the lampbrush chromosomes in the oocytes or polytene chromosomes, but also in the somatic cells which are capable of dividing mitotically.

Animals↗
PubMed1978

[Methods of histological treatment of the labyrinth].

The otic labyrinth presents one of the most difficult objects for histological investigations as it is situated in the thick layer of the temporal bone and has a very complex structure. At the same time, a method for treating this object is not given in general hand-books on pathological techniques. The methods for histological treatment of the otic labyrinth elaborated by Wittmaack and later on modified are presented in the article. Methods for fixation, vital fixation including, decalcination, dehydratation and saturation of the objects prepared for histological investigation are described in details. Methods for the temporal bone orientation in order to obtain sections of the internal otic structures in the most advantageous plane depending on the purpose and aim of the investigation are recommended.

Animals↗
PubMed1986

[Venous and meningeal prolapse during enlarged trans-labyrinth approach].

One hundred consecutive operations using the enlarged trans-labyrinthic (ETL) approach for acoustic neurinoma performed by the same surgeon were analyzed to determine incidence of venous and/or meningeal prolapses. Findings showed that ETL approaches were normal in 51 cases : normal superficial sinusodural space--external auditory canal and on deep dissection a superior petrous sinus and jugular space separated from the internal auditory canal. Prolapse was observed in 49 approaches : 30 very narrow sinusodural spaces due usually to temporal meninges prolapse (76%) associated in 25% of cases with a prolapse of lateral sinus; 29 prolapses of jugular space and 10 of superior petrous sinus, detected mainly in the narrow sinusodural spaces. In these cases, superficial displacement of the temporal meninges and lateral sinus appears indispensable in order to recover normal operating conditions towards the labyrinth and pontocerebellar angle.

Ear, Inner↗