Modified epidermal cells located in the stratum basale. They are found mostly in areas where sensory perception is acute, such as the fingertips. Merkel cells are closely associated with an expanded terminal bulb of an afferent myelinated nerve fiber. Do not confuse with Merkel's corpuscle which is a combination of a neuron and an epidermal cell.

A carcinoma arising from MERKEL CELLS located in the basal layer of the epidermis and occurring most commonly as a primary neuroendocrine carcinoma of the skin. Merkel cells are tactile cells of neuroectodermal origin and histologically show neurosecretory granules. The skin of the head and neck are a common site of Merkel cell carcinoma, occurring generally in elderly patients. (Holland et al., Cancer Medicine, 3d ed, p1245)

A species of POLYOMAVIRUS suspected to be the cause of most cases of MERKEL CELL CARCINOMA, a rare but highly lethal form of skin cancer.

Infections with POLYOMAVIRUS, which are often cultured from the urine of kidney transplant patients. Excretion of BK VIRUS is associated with ureteral strictures and CYSTITIS, and that of JC VIRUS with progressive multifocal leukoencephalopathy (LEUKOENCEPHALOPATHY, PROGRESSIVE MULTIFOCAL).

Tumors or cancer of the SKIN.

A genus of potentially oncogenic viruses of the family POLYOMAVIRIDAE. These viruses are normally present in their natural hosts as latent infections. The virus is oncogenic in hosts different from the species of origin.

A type I keratin expressed predominately in gastrointestinal epithelia, MERKEL CELLS, and the TASTE BUDS of the oral mucosa.

Infections produced by oncogenic viruses. The infections caused by DNA viruses are less numerous but more diverse than those caused by the RNA oncogenic viruses.

Those proteins recognized by antibodies from serum of animals bearing tumors induced by viruses; these proteins are presumably coded for by the nucleic acids of the same viruses that caused the neoplastic transformation.

Stiff hairs projecting from the face around the nose of most mammals, acting as touch receptors.

Cells specialized to transduce mechanical stimuli and relay that information centrally in the nervous system. Mechanoreceptor cells include the INNER EAR hair cells, which mediate hearing and balance, and the various somatosensory receptors, often with non-neural accessory structures.

MUCOUS MEMBRANE extending from floor of mouth to the under-surface of the tongue.

The outer covering of the body that protects it from the environment. It is composed of the DERMIS and the EPIDERMIS.

Facial neoplasms are abnormal growths or tumors that develop in the facial region, which can be benign or malignant, originating from various cell types including epithelial, glandular, connective tissue, and neural crest cells.

A non-template-directed DNA polymerase normally found in vertebrate thymus and bone marrow. It catalyzes the elongation of oligo- or polydeoxynucleotide chains and is widely used as a tool in the differential diagnosis of acute leukemias in man. EC 2.7.7.31.

Polyomavirus antigens which cause infection and cellular transformation. The large T antigen is necessary for the initiation of viral DNA synthesis, repression of transcription of the early region and is responsible in conjunction with the middle T antigen for the transformation of primary cells. Small T antigen is necessary for the completion of the productive infection cycle.

An acridine derivative formerly widely used as an antimalarial but superseded by chloroquine in recent years. It has also been used as an anthelmintic and in the treatment of giardiasis and malignant effusions. It is used in cell biological experiments as an inhibitor of phospholipase A2.

A general term collectively applied to tumors associated with the APUD CELLS series, irrespective of their specific identification.

One of the endogenous pentapeptides with morphine-like activity. It differs from LEU-ENKEPHALIN by the amino acid METHIONINE in position 5. Its first four amino acid sequence is identical to the tetrapeptide sequence at the N-terminal of BETA-ENDORPHIN.

Deoxyribonucleic acid that makes up the genetic material of viruses.

A type II keratin found associated with KERATIN-18 in simple, or predominately single layered, internal epithelia.

Branch-like terminations of NERVE FIBERS, sensory or motor NEURONS. Endings of sensory neurons are the beginnings of afferent pathway to the CENTRAL NERVOUS SYSTEM. Endings of motor neurons are the terminals of axons at the muscle cells. Nerve endings which release neurotransmitters are called PRESYNAPTIC TERMINALS.

An acidic protein found in the NEUROENDOCRINE SYSTEM that functions as a molecular chaperone for PROPROTEIN CONVERTASE 2.

The fraction of a blood sample, following CENTRIFUGATION, that is distinguished as a thin light-colored layer between the RED BLOOD CELLS, underneath it, and the PLASMA, above it. It is composed mostly of WHITE BLOOD CELLS and PLATELETS.

A MARVEL domain-containing protein found in the presynaptic vesicles of NEURONS and NEUROENDOCRINE CELLS. It is commonly used as an immunocytochemical marker for neuroendocrine differentiation.

Histochemical localization of immunoreactive substances using labeled antibodies as reagents.

A form of highly malignant lung cancer that is composed of small ovoid cells (SMALL CELL CARCINOMA).

The part of the face that is below the eye and to the side of the nose and mouth.

A tube-like invagination of the EPIDERMIS from which the hair shaft develops and into which SEBACEOUS GLANDS open. The hair follicle is lined by a cellular inner and outer root sheath of epidermal origin and is invested with a fibrous sheath derived from the dermis. (Stedman, 26th ed) Follicles of very long hairs extend into the subcutaneous layer of tissue under the SKIN.

The external, nonvascular layer of the skin. It is made up, from within outward, of five layers of EPITHELIUM: (1) basal layer (stratum basale epidermidis); (2) spinous layer (stratum spinosum epidermidis); (3) granular layer (stratum granulosum epidermidis); (4) clear layer (stratum lucidum epidermidis); and (5) horny layer (stratum corneum epidermidis).

Tumors or cancer of the LIP.

Sensation of making physical contact with objects, animate or inanimate. Tactile stimuli are detected by MECHANORECEPTORS in the skin and mucous membranes.

The specificity of a virus for infecting a particular type of cell or tissue.