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Results for “VESTIBULAR APPARATUS”

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PubMed1976

[Position and bony structures of the vestibular apparatus in the guinea pig].

The study of the inner ear of the guinea pig intended to give an explanation to what extent there are differences discernible in relation to the human labyrinth. Additional histological research should clarify the question, if structural differences exist in the osseous labyrinth capsule of the same animal. It has turned out that in normal headbearing the position of the semicircular canals deviates from the human vestibular apparatus. The semicircular canals are nearly vertical to each other, but in comparison to the human labyrinth they are shifted around the longitudinal axis of the utriculus caudal by ca. 30 degrees. In general the position of the vestibulo-cochlear organ is fixed to a great extent by the inclined course of the petrosal pyramid. This different position of the semicircular canals in man and animal is supposed to be due to the phylogenetic evolution and the adjustment to upright walk. Size and extension of the single semicircular canals are very different within the same animal. These differences in size indicate causalities of form and function. The relations in the build of the osseous labyrinth are extremely complicated. Compared to the other corporal regions the static parts of the petrosal pyramid are exceptional massive and of remarkable hard consistency. In the inner capsule of the ear there are three different bone strata to be seen. The characteristic lamel structure is most solid nearest to the semicircular canals. The fetal characteristics in the maturing process of the petrosal bone were traced a long while in the postnatal life. The typical building of the labyrinthal bone structures contributes to the mechanical stability of the capsule.

Animals↗
PubMed1984

"Spinner" cephalopods: defects of statocyst suprastructures in an invertebrate analogue of the vestibular apparatus.

Individuals of seven species of coleoid cephalopods (three species of octopus, three of squid, and one of cuttlefish), that were cultured and reared in laboratory aquarium systems, had a behavioral defect at hatching which was characterized by an inability to control orientation while swimming. These defective animals were designated as "spinners." An examination of statocysts from individuals of five of the affected species revealed abnormalities of the neuro-epithelial suprastructures: absence or malformation of the statolith of the gravity receptor system and absence of the cupulae of the angular acceleration receptor systems. The sensory epithelia did not differ from those of normal animals, nor did the synaptic structures and relationships, when examined both with scanning and transmission electron microscopy. The abnormalities were compared with congenital defects of the neuropeithelial suprastructures of the vestibular apparatus (especially in mammals). The defects observed in statocysts of spinner animals are thought to be the result of environmental causes, such as the temperature or chemistry of the seawater in the transportation vessels or rearing systems, rather than genetic causes.

Animals↗
PubMed1992

Computer-aided three-dimensional measurement of the human vestibular apparatus.

Using a computer-aided three-dimensional reconstruction and measurement method, 12 measurements were made to determine the dimensions of the maculae, cristae ampullares, and semicircular canals in 18 temporal bones from nine pairs of age-matched male and female individuals (1 day to 76 years old). The surface areas of the utricular and saccular maculae were significantly larger in male than in female specimens (two-way analysis of variance, F = 9.00, df = 1, p less than 0.01; F = 4.57, df = 1, p less than 0.05, respectively). The width of the utricular macula and the length of the saccular macula were also significantly greater in male than in female specimens (two-way analysis of variance, F = 5.17, df = 1, p less than 0.05; F = 4.33, df = 1, p less than 0.05, respectively). Finally, the three semicircular canals were larger in diameter in male vs. female specimens; this difference was statistically significant for the superior semicircular canal (two-way analysis of variance, F = 10.74, df = 1, p less than 0.01). By contrast, none of these dimensions of those vestibular structures showed any significant change in size with advancing postnatal age. We propose from these findings that there appears to be sexual dimorphism in the vestibular apparatus.

Adolescent↗
PubMedDate not supplied

[The turning reflex, static endurance and structure of the vestibular apparatus receptors in rats exposed to whole-body low-frequency vibration].

Wistar rats were for 2 weeks exposed to vibrations of 18 Hz (acceleration of 2.3 G applied for 5.8 hrs a day for as long as 58 hrs) and 30 Hz (acceleration of 9.6 G applied for 5.1 hrs a day for as long as 56 hrs). The weight gain of experimental animals was less than that of control rats. Static endurance measured in terms of the time, during which the rats stayed on the vertical pole, decreased in the controls as their weight grew. Static endurance of the experimental rats remained essentially unchanged in spite of their growth. This may be associated with the stimulating effect of vibration on the muscle tone. The turning reflex was investigated using a specially designed unit, which allowed stroboscopic photography that was synchronized with the moment, when the animal began to fall down. The angles between the head and torso as related to the horizontal line were calculated and found to be unaltered in both experimental and control animals during 2 weeks. However, after exposure to vibration of both magnitudes the rats began to position the body off the horizontal line. Morphological examinations revealed no distinct structural changes in the utriculus, sacculus or posterior ampulla of the experimental rats when compared with the controls. At the same time it was demonstrated that the exposure produced swelling of cupulate nerve endings in the central compartment of the receptor epithelium of the posterior ampulla. The time course of morphofunctional changes of the vestibular apparatus in response to vibration of different frequencies (from 6 to 50 Hz) was also examined.

Animals↗