Stereocilia (inner ear)

Stereocilia (inner ear)

Stereocilia in the inner ear are small, stiff, hair-like structures that are found on the top (apical surface) of hair cells in the organ of Corti and the vestibular system of the inner ear. They are not true cilia because they do not have the typical 9+2 structure of microtubules. Instead, they are filled with tightly packed actin filaments, which are anchored at the top by a dense body and at the base by a rootlet.

Structure and Function

Stereocilia are arranged in a staircase pattern of increasing height. They are interconnected by a series of tip links and horizontal top connectors. When sound vibrations or head movements cause the basilar membrane to move, this movement is transferred to the stereocilia, causing them to tilt and triggering the opening of mechanotransduction channels at the tips of the stereocilia. This allows potassium and calcium ions to flow into the hair cell, leading to depolarization and the release of neurotransmitters that stimulate the auditory nerve.

Clinical Significance

Damage to the stereocilia can lead to hearing loss and balance disorders. This can be caused by exposure to loud noise, certain medications (ototoxic drugs), and aging. In some cases, genetic mutations can also cause defects in the structure or function of the stereocilia, leading to congenital hearing loss.

See Also

• Hair cell
• Organ of Corti
• Vestibular system
• Mechanotransduction
• Hearing loss

References

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