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Stereocilia (or stereovilli or villi) are non-motile apical cell modifications. They are distinct from cilia and microvilli , but are closely related to microvilli. They form single "finger-like" projections that may be branched, with normal cell membrane characteristics.
In the inner ear, stereocilia are the mechanosensing organelles of hair cells, which respond to fluid motion in numerous types of animals for various functions, including hearing and balance. They are about 10–50 micrometers in length and share some similar features of microvilli . [ 1 ]
The destruction of microvilli can actually be beneficial sometimes, as in the case of elimination of microvilli on white blood cells which can be used to combat auto immune diseases. [ 6 ] Congenital lack of microvilli in the intestinal tract causes microvillus atrophy , a rare, usually fatal condition found in new-born babies.
In therian mammals, the lagena is extended still further, becoming a coiled structure (cochlea) in order to accommodate its length within the head. The organ of Corti also has a more complex structure in mammals than it does in other amniotes. [12] The arrangement of the inner ear in living amphibians is, in most respects, similar to that of ...
The hair bundle is composed of stiff microvilli called stereocilia and is involved with mechanoreception of sound waves. Stereocilia cells generate an electrical response to the vibrations of sound waves, crucial for normal hearing. This gene is part of a tandem duplication on chromosome 15; the second copy is a pseudogene.
Outer hair cells are a motor structure. Sound energy causes changes in the shape of these cells, which serves to amplify sound vibrations in a frequency specific manner. Lightly resting atop the longest cilia of the inner hair cells is the tectorial membrane , which moves back and forth with each cycle of sound, tilting the cilia, which is what ...
Other cellular extensions that protrude from the cell membrane are known as membrane protrusions or cell protrusions, also cell appendages, such as flagella, and microvilli. [ 8 ] [ 9 ] Microtentacles are cell protrusions attached to free-floating cells, associated with the spread of some cancer cells .
Contrasting with stereocilia, which are numerous, there is only one kinocilium on each hair cell. The kinocilium can be identified by its apical position as well as its enlarged tip. [1] Together with stereocilia, the kinocilium regulates depolarization and hyperpolarization of the hair cell, which is a neuron that can generate action ...