Kinocilium
| Kinocilium | |
|---|---|
| Details | |
| Latin | Kinocilium |
| TH | H1.00.01.1.01015 |
|
Anatomical terminology
[]
|
|
A kinocilium is a special type of cilium on the apex of hair cells located in the sensory epithelium of the vertebrate inner ear.
Kinocilia are found on the apical surface of hair cells and are involved in both the morphogenesis of the hair bundle and mechanotransduction. Vibrations (either by movement or sound waves) cause displacement of the hair bundle, resulting in depolarization or hyperpolarization of the hair cell. The depolarization of the hair cells in both instances causes signal transduction via neurotransmitter release.
Each hair cell has a single, microtubular kinocilium. Before morphogenesis of the hair bundle, the kinocilium is found in the center of the apical surface of the hair cell surrounded by 20-300 microvilli. During hair bundle morphogenesis, the kinocilium moves to the cell periphery dictating hair bundle orientation. As the kinocilium moves, microvilli surrounding it begin to elongate and form actin stereocilia. In many mammals the kinocilium will regress once the hair bundle has matured.
The movement of the hair bundle, as a result of endolymph flow, will cause potassium channels on the stereocilia to open. This is mostly due to the pulling force stereocilia exerts on its neighboring stereocilia via interconnecting links that hold stereocilia together (usually from tallest to shortest) and this leads to the depolarization of the hair cell. This pattern of depolarization should not be confused with the more common depolarization which involves the influx of Na+ into the cell while K+ channels stay closed. Endolymph composition resembles that of the intracellular fluid (more K+ and less Na+) more closely compared to its counterpart, perilymph which resembles the extracellular fluid (more Na+ and less K+ compared to intracellular matrix). This depolarization will open voltage gated calcium channels. The influx of calcium then triggers the cell to release vesicles containing excitatory neurotransmitters into a synapse. The post-synaptic neurite then sends an action potential to the Scarpa's ganglion.
...
Wikipedia