Otolith

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Related to otolithic: utriculus, utricles

otolith

[′ōd·ə‚lith]
(anatomy)
A calcareous concretion on the end of a sensory hair cell in the vertebrate ear and in some invertebrates.

Otolith

 

a solid formation on the surface of the mechanoreceptor cells in the organs of equilibrium of some invertebrates and all vertebrates. Otoliths of different animals vary in origin, size, and structure: they can be secreted by cells or introduced from outside, for example, grains of sand serve as otoliths in crayfish. Mammalian otoliths are usually crystals of calcite (CaCO3) up to 10 microns (μ.) long and 1–3 μ wide.

As otoliths shift in response to acceleration and changes in body position, they mechanically irritate the underlying ciliated receptor cells, which then send appropriate signals to the brain.

The action of otoliths has been demonstrated in experiments with crayfish. The grains of sand that serve as the crayfish’s otoliths were replaced during molting by iron filings, and a magnet was placed above the animal to attract the filings. The crayfish reversed its sense of orientation, turned over, and swam with its abdomen up.

O. B. IL’INSKII

References in periodicals archive ?
Other studies of the otolithic organs, the detectors of linear movement, are exploring how these organs differentiate between downward (gravitational) motion from linear (forward-to-aft, side-to-side) motion.
In individuals over 60 years, the degeneration seen in the sensory epithelia of the saccule is matched by a reduction in the calcium carbonate crystals (`otoconia') which exert an inertial force on the hair cells, resulting in an otolithic membrane which is bare.
Rogers proposes that a goldfish's otolithic organs act somewhat like accelerometers, which provide information about a body's velocity in various directions.
Benign paroxysmal positional vertigo is a condition that is caused by movement of otolithic debris or granules within the semicircular canals.
Most otolaryngologists do not have a close familiarity with clinical tests such as the head-shake test, the oscillopsia (dynamic visual acuity) test, the high-frequency horizontal head-thrust (Halmagyi) maneuver, and the head-heave translational otolithic maneuver.
Acoustic particle motions of these sounds can be detected by the saccule, an otolithic endorgan having an auditory function in toadfish (3).
This event provokes a utricular response similar to that believed to precipitate a drop attack (Tumarkin's otolithic crisis) in patients with long-standing Meniere's disease.
These cells are organized in various orientations on the otolithic end-organs of fishes.
These findings were consistent in all 10 of our study patients, and they suggest that otolithic function might be involved in the functional deficit related to vestibular neuritis.