Myoepithelial cells (sometimes referred to as myoepithelium) are cells usually found in glandular epithelium as a thin layer above the

basement membrane The basement membrane is a thin, pliable sheet-like type of extracellular matrix that provides cell and tissue support and acts as a platform for complex signalling. The basement membrane sits between Epithelium, epithelial tissues including mesot ...

but generally beneath the luminal cells. These may be positive for

alpha smooth muscle ACTA2 (actin alpha 2) is an actin protein with several aliases including alpha-actin, alpha-actin-2, aortic smooth muscle or alpha smooth muscle actin (α-SMA, SMactin, alpha-SM-actin, ASMA). Actins are a family of globular multi-functional prote ...

actin and can contract and expel the secretions of exocrine glands. They are found in the

sweat gland Sweat glands, also known as sudoriferous or sudoriparous glands, , are small tubular structures of the skin that produce sweat. Sweat glands are a type of exocrine gland, which are glands that produce and secrete substances onto an epithelial sur ...

s, mammary glands, lacrimal glands, and salivary glands. Myoepithelial cells in these cases constitute the

basal cell layer The ''stratum basale'' (basal layer, sometimes referred to as ''stratum germinativum'') is the deepest layer of the five layers of the epidermis, the external covering of skin in mammals. The ''stratum basale'' is a single layer of columnar or ...

of an

epithelium Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellul ...

that harbors the epithelial

progenitor In genealogy, the progenitor (rarer: primogenitor; german: Stammvater or ''Ahnherr'') is the – sometimes legendary – founder of a family, line of descent, clan or tribe, noble house, or ethnic group.. Ebenda''Ahnherr:''"Stammvater eines G ...

. In the case of wound healing, myoepithelial cells reactively proliferate. Presence of myoepithelial cells in a hyperplastic tissue proves the benignity of the gland and, when absent, indicates cancer. Only rare cancers like adenoid cystic carcinomas contains myoepithelial cells as one of the malignant component. It can be found in

endoderm Endoderm is the innermost of the three primary germ layers in the very early embryo. The other two layers are the ectoderm (outside layer) and mesoderm (middle layer). Cells migrating inward along the archenteron form the inner layer of the gast ...

ectoderm The ectoderm is one of the three primary germ layers formed in early embryonic development. It is the outermost layer, and is superficial to the mesoderm (the middle layer) and endoderm (the innermost layer). It emerges and originates from t ...

Markers

Myoepithelial cells are true

epithelial cell Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellula ...

s positive for keratins, not to be confused with myofibroblasts which are true mesenchymal cells positive for vimentin. These cells are generally positive for

actin (αSMA), cytokeratin 5/6 and other high molecular weight cytokeratins, p63 and caldesmon. Myoepithelial cells are stellate in shape and are also known as basket cells. They lie between the basement membrane and glandular epithelium. Each cell consists of a cell body from which 4-8 processes radiate and embrace the secretory unit. Myoepithelial cells have contractile functions. They help in expelling secretions from the lumen of secretory units and facilitate the movement of saliva in salivary ducts.

Other Cancers Involving This Type of Cell

* Myoepithelioma of the head and neck - A (usually) benign tumor of the head/neck consisting of solely myoepithelial cells. * Epithelial-myoepithelial carcinoma (of the salivary glands) - A low-grade malignant tumor composed of both neoplastic epithelial and neoplastic myoepithelial cells (a biphasic tumor). *

Epithelial-myoepithelial carcinoma of the lung Epithelial-myoepithelial carcinoma of the lung is a very rare histologic form of malignant epithelial neoplasm ("carcinoma") arising from lung tissue. Genetics The epithelial component in EMECL's typically strongly express cytokeratins, but are ...

- A malignant tumor composed of both epithelial and myoepithelial tissues whose pathology resemble salivary cells. *

Adenomyoepithelioma of the breast An adenomyoepithelioma of the breast is a rare tumour in the breast composed of glandular elements (adeno-) and myoepithelial cells. It is usually benign; however, there are reports of malignant behaviour. The histomorphologic appearance can mi ...

- A (usually) benign tumor of the breast composed of Myoepithelial and

Adeno In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). Structure De ...

(glandular) cells. * Myoepithelioma of the Breast- A usually benign or exceedingly rare malignant tumor of the breast which mimics IDC but with cells resembling adenoid cysts. If malignant, this is also known as a Myoepithelial Carcinoma.

References

External links

* - "Axillary Sweat Gland: Myoepithelium" * - "thick skin" * "Simple Tubular Coiled" * Cell biology Epithelial cells {{anatomy-stub