Alopecia: Absence of hair from areas where it is normally present.Alopecia Areata: Loss of scalp and body hair involving microscopically inflammatory patchy areas.Scalp: The outer covering of the calvaria. It is composed of several layers: SKIN; subcutaneous connective tissue; the occipitofrontal muscle which includes the tendinous galea aponeurotica; loose connective tissue; and the pericranium (the PERIOSTEUM of the SKULL).Hair Follicle: 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.Hair: A filament-like structure consisting of a shaft which projects to the surface of the SKIN from a root which is softer than the shaft and lodges in the cavity of a HAIR FOLLICLE. It is found on most surfaces of the body.Minoxidil: A potent direct-acting peripheral vasodilator (VASODILATOR AGENTS) that reduces peripheral resistance and produces a fall in BLOOD PRESSURE. (From Martindale, The Extra Pharmacopoeia, 30th ed, p371)Haptophyta: A group (or phylum) of unicellular EUKARYOTA (or algae) possessing CHLOROPLASTS and FLAGELLA.Folliculitis: Inflammation of follicles, primarily hair follicles.Dermoscopy: A noninvasive technique that enables direct microscopic examination of the surface and architecture of the SKIN.Tinea Capitis: Ringworm of the scalp and associated hair mainly caused by species of MICROSPORUM; TRICHOPHYTON; and EPIDERMOPHYTON, which may occasionally involve the eyebrows and eyelashes.Trichotillomania: Compulsion to pull out one's hair.Cicatrix: The fibrous tissue that replaces normal tissue during the process of WOUND HEALING.Photophobia: Abnormal sensitivity to light. This may occur as a manifestation of EYE DISEASES; MIGRAINE; SUBARACHNOID HEMORRHAGE; MENINGITIS; and other disorders. Photophobia may also occur in association with DEPRESSION and other MENTAL DISORDERS.Lichen Planus: An inflammatory, pruritic disease of the skin and mucous membranes, which can be either generalized or localized. It is characterized by distinctive purplish, flat-topped papules having a predilection for the trunk and flexor surfaces. The lesions may be discrete or coalesce to form plaques. Histologically, there is a "saw-tooth" pattern of epidermal hyperplasia and vacuolar alteration of the basal layer of the epidermis along with an intense upper dermal inflammatory infiltrate composed predominantly of T-cells. Etiology is unknown.Eyebrows: Curved rows of HAIR located on the upper edges of the eye sockets.Triethylenephosphoramide: An insect chemosterilant and an antineoplastic agent.Hypotrichosis: Presence of less than the normal amount of hair. (Dorland, 27th ed)Skin: The outer covering of the body that protects it from the environment. It is composed of the DERMIS and the EPIDERMIS.Ichthyosis: Any of several generalized skin disorders characterized by dryness, roughness, and scaliness, due to hypertrophy of the stratum corneum epidermis. Most are genetic, but some are acquired, developing in association with other systemic disease or genetic syndrome.Sebaceous Glands: Small, sacculated organs found within the DERMIS. Each gland has a single duct that emerges from a cluster of oval alveoli. Each alveolus consists of a transparent BASEMENT MEMBRANE enclosing epithelial cells. The ducts from most sebaceous glands open into a HAIR FOLLICLE, but some open on the general surface of the SKIN. Sebaceous glands secrete SEBUM.