Cobblestoning: “Plugs” that have not healed flush with the skin and therefore have left the scalp lumpy. “Plugs” seldom heal flush with the skin. Cobblestoning occurs in almost all “plug” procedures.
Cortex: The layer of the hair shaft that surrounds the medulla and is filled with keratin fibers. The main structural part of the hair fiber that accounts for most of its size and strength.
Crown: The highest part of the head.
Cuticle: The outer surface of hair, composed of overlapping scales made of colorless keratin protein. It gives hair luster and shine and also provides some of its strength.
Dermal Papilla: The dermal papilla is situated at the base of the hair follicle. The dermal papilla contains nerves and blood vessels, which supply glucose for energy and amino acids to make keratin. This structure is extremely important in the regulation of hair growth since it has receptors for both androgens and hair-promoting agents.
Dermis: One of the two layers of cells that form skin. Specifically, it is the innermost layer.
Diazoxide: A drug that dilates blood vessels by opening potassium channels and also promotes hair growth.
Dihydrotestosterone (DHT): Male hormone thought to be the main cause for the miniaturization of the hair follicle and for hair loss. DHT is formed when the male hormone testosterone interacts with the enzyme 5-alpha reductase.
Donor Site: Area where pieces of hair-bearing skin are taken from during a hair transplant.
Double Blind Study: A scientific study where neither the subjects nor the researchers know who specifically is receiving the drug of treatment under study.
Dutasteride: A 5-alpha-reductase inhibitor medication by GlaxoSmithKline. Dutasteride inhibits both type-I and type-II 5-alpha reductase.
Epidermis: The outer protective, nonvascular layer of the skin
Estrogen: The female hormone secreted primarily by the ovaries.
Female Pattern Baldness (FPB): Progressive thinning of hair throughout the entire head caused by genes, age, and hormones. It usually develops at a much slower rate than male pattern baldness.
5-Alpha-Reductase: The chemical that is responsible for transforming testosterone into dihydrotestosterone.
5-Alpha-Reductase Inhibitors: Prevent the body from converting testosterone to dihydrotestosterone by blocking the action of the enzyme 5-alpha reductase.
Finasteride: The generic name of the brand name drug Proscar. Proscar is manufactured by Merck and is FDA approved for the treatment of benign prostate enlargement. 1mg tablets of finasteride have been marketed under the brand name Propecia as a treatment for hair loss. It is an antiandrogen that blocks the formation of dihydrotestosterone by inhibiting the enzyme 5-alpha reductase.
Flap: A type of hair replacement surgery in which a piece of hair-bearing scalp is cut on three or four sides and transplanted onto bald areas of the scalp. Follicle: A saclike structure just below the surface of your scalp. It is the sheath within which hair grows.