Stereocilia (or stereovilli or villi) are non-motile apical cell modifications. They are distinct from

cilia The cilium, plural cilia (), is a membrane-bound organelle found on most types of eukaryotic cell, and certain microorganisms known as ciliates. Cilia are absent in bacteria and archaea. The cilium has the shape of a slender threadlike proje ...

and

microvilli Microvilli (singular: microvillus) are microscopic cellular membrane protrusions that increase the surface area for diffusion and minimize any increase in volume, and are involved in a wide variety of functions, including absorption, secretion, ...

, but are closely related to microvilli. They form single "finger-like" projections that may be branched, with normal cell membrane characteristics. They contain

actin Actin is a family of globular multi-functional proteins that form microfilaments in the cytoskeleton, and the thin filaments in muscle fibrils. It is found in essentially all eukaryotic cells, where it may be present at a concentration of ov ...

. Stereocilia are found in the vas deferens, the

epididymis The epididymis (; plural: epididymides or ) is a tube that connects a testicle to a vas deferens in the male reproductive system. It is a single, narrow, tightly-coiled tube in adult humans, in length. It serves as an interconnection between the ...

, and the sensory cells of the

inner ear The inner ear (internal ear, auris interna) is the innermost part of the vertebrate ear. In vertebrates, the inner ear is mainly responsible for sound detection and balance. In mammals, it consists of the bony labyrinth, a hollow cavity in th ...

Structure

Stereocilia are cylindrical and non-motile. They are much longer and thicker than

, form single "finger-like" projections that may be branched, and have more of the characteristics of the cellular membrane proper. Like microvilli, they contain

and lack an axoneme. This distinguishes them from

. They do not have a Basal body at their base since they do not contain microtubules. They may or may not be covered by a

glycocalyx The glycocalyx, also known as the pericellular matrix, is a glycoprotein and glycolipid covering that surrounds the cell membranes of bacteria, epithelial cells, and other cells. In 1970, Martinez-Palomo discovered the cell coating in animal c ...

coating. They have no fixed arrangement, different to the structure present in kinocilium.

Function

Stereocilia are found in: *the vas deferens. * the

. Some consider epididymal stereocilia to be a variant of microvilli, rather than their own distinct type of structure. *the sensory (hair) cells of the

References

External links

J.A. Illingworth, "Sensory Transducers" (Lectures, 2011), University of Leeds
{{Authority control Histology Actin-based structures