Glossary Terms
Below is a list of words used to refer to something related to hair loss / hair transplantation from A to Z (V in this case). Feel free to use it as a guide. (If you have a suggestion that you think would be helpful, please email us so that we can review it and add it.)
A
Alopecia: [Gk, alopex, fox (mange)], partial or total loss of hair due to different diseases or conditions.
Alopecia Androgenetica: [Gk, alopex, fox (mange) + Gk, andros + genein, to be produced], medical name for male or female pattern baldness.
Alopecia Areata: [Gk, alopex, fox (mange) + L, area, open area], hair loss in clearly marked areas.
5 alpha-reductase: the enzyme required to transform testosterone to dihydrotestosterone (DHT). Type 1 5-alpha reductase is found primarily in the skin and type 2 5-alpha reductase is primarily found in the prostate.
Anagen: [Gk, ana, up, again + genein, to be produced], the rising phase of the hair, which shows great variability, ranging from two to six years or more.
Androgen: [Gk, andros + genein, to be produced], any steroid hormone that increases male characteristics.
Apoptose: [Gk, apo, separation + ptosis, falling], programmed cell death.
Azelaic acid: natural saturated dicarboxylic acid with a chemical name of 1,7-heptanedicarboxylic acid and a molecular weight of 188,22. Azelaic acid is a dietary component of whole-grain cereals and animal products. Azelaic acid (0.1 to 3.0 mmol / l) has been shown to produce a competitive concentration-dependent inhibition of 5-alpha reductase activity.
B
Biopsy: [Gk, biology, life + opsis, vision], removal of a small piece of living tissue from the organ or other part of the body for microscopic examination.
C
Catagen: [Gk, kata, down, under + genein, to be produced], the brief transition period of the hair growth cycle, lasting two to three weeks.
Clone: [Gk, clone, plant cutting], a group of genetically identical cells or species originating from a single common cell.
Crown: [L, crown, encircling structure], the upper portion of the organ or structure, such as the upper part of the ear.
Cuticule: the outer surface of the scalp, consisting of overlapping scales made of colorless keratin protein. It gives shine and elegance to the hair and also gives some of its energy.
D
Dermal Papilla: The dermal papilla is found at the base of the hair follicle. Dermal papilla comprises nerves and blood vessels that supply glucose for energy and amino acids to create keratin. This structure is extremely important in the regulation of hair growth, because it has receptors for both androgens and hair promoters.
Dermatology: [Gk, derma, skin + logos, science], skin research, including anatomy, physiology, and skin pathology, and diagnosis and treatment of skin disorders.
Dermis: [Gk, derma, skin], skin layer just below the epidermis, consisting of papillary and reticular layers and comprising blood and lymphatic vessels, nerves and nerve ends, glands and hair follicles.
DHT: dihydrotestosterone acronym. Classified as a sex hormone, there is no well-defined connection to the levels of DHT and libido or sexual activity. Apart from encouraging hair growth in the face and upper pubis (but having the opposite effect on the scalp), the role of DHT in adult males is a mystery.
Donor region: region of the scalp (usually along the sides) where the hair is removed to be transplanted to the bald area.
Dutasteride: a drug currently under development by GlaxoSmithKline, a dual inhibitor of 5-alpha reductase enzymes responsible for transforming testosterone to DHT.
E
Effluvium: [L, effluvium, outflow], outflow, which can cause sudden, extreme hair loss.
Epidermis: [Gk, epi, on or on + derma, skin], shallow, avascular, layers of skin, formed by an outer, dead cornified portion and a lower, living, cellular portion. Altogether, these layers are between 0.5 and 1.1 mm. Etiology: [Gk, hasia, cause + logos, science], cause of disease.
F
Finasteride: the common name for Propecia and Proscar, which are medicines that bind to the type 2 5-alpha reductase enzyme and reduce the amount of DHT in the prostate and serum.
Follicle: [L, follicle, tiny bag], a pouch like depression, such as hair follicles within the dermis that enclose the roots of the hair.
Frontal hairline: [L, fons, forehead], the demarcation of the vellus to the terminal or intermediate hair in and adjacent to the midline of the anterior part of the head.
G
Generic: [L, genus, type], of or referring to a substance, product or medication not covered by a trademark; similar in chemical composition but not necessarily equivalent in therapeutic effect.
Glycerin or glycerin: [Gk, glycerol, smooth], a smooth, colorless, oily fluid that is a pharmacological classification of glycerol. Glycerin is used as a moisturizing agent for chapped skin, as an component in constipation suppositories and as a sweetening agent and as a medium for the preparation in medicines.
H
Hamilton-Norwood: a visual scale reflecting the degree of hair loss / recession of androgenetic alopecia in males.
Hirsutism: [L, hirsutus, hair], excess body or facial hair due to heredity, hormonal imbalance, porphyria or treatment. Often referred to as hypertrichosis.
Hormone: [Gk, hormaein, to set in motion], a complex chemical formed in one part or organ of the body that initiates or controls the function of an organ or a group of cells in another part of the body.
Hypertrichosis: excessive hair growth over and above average for an individual’s age, sex and race, as opposed to hirsutism, which is an excess of hair growth in women following a male pattern of distribution. Hypertrichosis may occur across the body or may be confined to small areas.
Hypothyroidism: (underactive thyroid gland) is the term used to describe a disorder in which there is a reduced level of thyroid hormone (thyroxine) in the body. This can cause a number of symptoms, including: tiredness, weight gain, constipation, aches, dry skin, dull hair / hair loss, and feeling cold.
I
Idiopathic: [Gk, idiosynthesis, private, distinctive, unusual + pathos, disease], without a known cause.
Infundibulum: is the cup or funnel in which the hair follicle develops, often the upper or upper portion of the hair follicle.
Intermediate Hair: the intermediate scalp hair is approximately 1 cm long. They lack the structure of the terminal hair, but they have a much thicker body than the velvet hair.
In Vitro: [L, in, within + vitreous, glassware], a biologic reaction occurring in the laboratory apparatus.
In Vivo: [L, in, inside + vivo, alive], a biologic reaction occurring in a living organism.
K
Keratin: [Gk, keras, horn], a fibrous, sulphur-containing protein that is the primary component of the epidermis, hair, nails and teeth enamel.
Ketoconazole: an antifungal drug that prevents the biosynthesis of ergosterols or other sterols.
L
Ludwig Staging: a vivid illustration of the extent of androgenetic alopecia in women, originally published in the British Journal of Dermatology in 1977.
Lunago: [L, down], light, fine hair that covers a lot of the foetus beginning in the fifth month and is normally shed before birth.
M
Micrograft: [Gk, micros, small] stands for grafts with 1 or 2 hairs, minigrafts are those with 3 or 4 hairs, and megasession is a process in which more than 1000 micrografts and minigrafts are implanted in a single session.
Midline: the area in the center of the scalp.
Miniaturization: a harmful mechanism by which dihydrotestosterone (DHT) shrinks hair follicles; a key marker for androgenetic alopecia.
Minoxidil: a piperidinopyrimidine derivative vasodilator with stimulating hair growth properties, likely involving direct stimulation of epithelial hair follicle growth. The first FDA drug to be approved for the treatment of MPB.
O
Occiput: [L, occiput, atlas], the back of the ear.
Oestrogen: [Gk, oistros, gadfly + genein, to be produced], one of a group of hormonal steroid compounds that facilitate the production of female secondary sex characteristics.
P
Papilla: a small root area at the base of the hair that receives the nutrients required for hair growth.
Pharmacodynamics: [Gk, pharmakon, drug + dynamism, power], study of how a medication works on a living organism.
Posterior Scalp: the skin on the back of the head.
Pilosebaceous Unit: [L, pill, hair + sebum, fat], of or relating to a hair follicle and its oil gland.
Proprietary: [L, proprietas, property], of or pertaining to a commodity, such as a drug or tool, made for profit.
Propylene Glycol: a colorless viscous substance used as a solvent in the preparation of many medicines. This also prevents the development of fungi and micro-organisms.
R
Receptor Site: [L, recipere, to obtain + site, position], position on a cell surface where other molecules, such as enzymes, neurotransmitters, or viruses, are attached to communicate with cellular components.
Recession: [L, recedere, retreat], recession.
Recipient Site: The bald region in which the hair collected (usually from the donor region) is transplanted.
Retin-A: generic name for the preparation of retinoic acid used in the treatment of acne and sun damage to the skin Retinoic acid (also tretinoic acid, isotretinoic acid or all-trans-retinoic acid): cis-trans form of vitamin A. Retinoids function as a mild chemical skin peel and are very essential to all epithelial structures.
S
Scleroderma: [Gk, skliro, stiff, dermal, skin], persistent hardening and contraction of the skin and connective tissue, either locally or across the body. It can cause hair loss in the affected areas.
Sebaceous: [L, sebum, sweat], salty, sticky or greasy, generally referring to the oil-securing glands of the skin or to their secretions.
Sebum: [L, fat], oily secretion of the sebaceous glands of the skin, consisting of keratin, fat and cell waste.
Steroid: [Gk, stereos, solid + eidos, form], any of a large number of hormonal substances of identical basic chemical structure, formed primarily in the adrenal cortex and gonads.
Superoxide Dismutase (SOD): a chemical that catalyzes the degradation of oxygen free radicals. It defends oxygen-metabolizing cells against the adverse effects of free superoxide radicals.
Suture: the knot.
T
Telogen: [Gk, telos, end + genein, to be produced], the resting period of the hair growth cycle lasting approximately 100 days.
Temples or temples: [L, tempus, temple], the lateral-frontal regions of the brain.
Terminal Hair: [L, terminus, boundary] of or referring to the thicker hair on the scalp that has been medullated for several years.
Testosterone: a naturally occurring androgen hormone.
Donor Superiority Theory: A theoretical rationale for hair transplantation that suggests that the genetic code of the hair is inside the hair follicle and not at the recipient site where it is transplanted.
Trichotillomania: [Gk, trichos, hair, tillein, take out (hair)] a compulsive compulsion to take out one’s hair.
V
Vellus: smooth, fine hair covering all parts of the body except hands, soles and areas where other hair styles are usually found. True vellus hairs have no erectile pili muscle, but they have large sebaceous glands. Vellus scalp hairs are less than 1 cm long.
Vertex: [L, vertex, summit], the top of the head towards the back, including the area or areas where the hair develops in a spiral pattern.
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