A<unk>  is a parasitic fungus that infects the skin.  The term embraces the imperfect fungi of the genera Epidermophyton, Microsporum and Trichophyton.<unk> s (name based on the Greek for 'skin plants') are a common label for a group of three types of fungus that commonly causes skin disease in animals and humans. These anamorphic (asexual or imperfect) genera are: Microsporum, Epidermophyton and Trichophyton.  There are about 40 species in these three genera.  Species capable of reproducing sexually belong in the teleomorphic genus, Arthroderma, of the Ascomycota.  (See Teleomorph, anamorph and holomorph for more information on this type of fungal life cycle).<unk> s cause infections of the skin, hair and nails due to their ability to obtain nutrients from keratinized material. The organisms colonize the keratin tissues and inflammation is caused by host response to metabolic by-products. They are usually restricted to the nonliving cornified layer of the epidermis because of their inability to penetrate viable tissue of an immunocompetent host.  Invasion does elicit a host response ranging from mild to severe. Acid proteinases, elastase, keratinases, and other proteinases reportedly act as virulence factors. The development of cell-mediated immunity correlated with delayed hypersensitivity and an inflammatory response is associated with clinical cure, whereas the lack of or a defective cell-mediated immunity predisposes the host to chronic or recurrent<unk>  infection.
Some of these infections are known as ringworm or tinea. Toe- and fingernail infection are referred to as onychomycosis.<unk> s usually do not invade living tissues, but colonize the outer layer of the skin. Occasionally the organisms do invade subcutaneous tissues, resulting in kerion development.
Dermatophyte
Clavicle
Speculum
Ovum
Spore
Sporophyte
Slug
Blastocyst