Infundibulum: The superior, or highest portion, of the hair follicle.

Intermediate Hairs: Hairs that are in a growth stage between vellus (baby or immature) hair, such as on your face, and mature hair stage of growth such as the hair on the scalp.

Isthmus: The middle region of the hair follicle which usually contains the sebaceous gland.

Juri Flap: Surgical procedure that takes a large section of hair-bearing scalp from the side of the scalp and rotates it 180 degrees to the front, forming a hairline.

Keratin: A tough, fibrous, insoluble protein forming hair and finger nails.

Ketoconazole: An antifungal agent that has anti-androgenetic properties. Active ingredient in the shampoo Nizoral.

Lanugo Hair: The downy hair on the body of the fetus and newborn baby. Resembles vellus hair, soft and unpigmented.

Linear Graft: A row of hair and skin that is transplanted onto bald regions (outdated procedure).

Male Pattern Baldness (MPB): The most common type of hair loss; caused by hormones, genes, and age, it is usually progressive in nature. It affects the central and frontal area of the scalp and often results in a pronounced U-shape configuration.

Medulla: A central zone of cells present only in large, thick hairs.

Melanin: Pigmenting granules within the keratin fibers of the hair shaft that determine hair color. They usually decrease with age, resulting in gray or white hair.

Melanocyte: A specialized cell containing pigment (melanin), which determines hair color.

Menopause: The permanent cessation of menstruation and estrogen secretion from a woman’s ovaries.

Micrograft: A very small hair graft consisting of one or two hairs.

Midline: Region toward the middle of the scalp.

Miniaturization: The destructive process by which dihydrotestosterone (DHT) shrinks hair follicles; a key marker of androgenetic alopecia.

Minigraft: A small hair graft consisting of three to eight follicles each.

Minoxidil: A prescription medication taken orally for the treatment of high blood pressure and used topically to retard hair loss and/or encourage hair growth. Generic name for Rogaine.

Nonscarring Alopecia: A broad category of different types of hair loss, including androgenetic alopecia. The hair follicle remains intact, thus increasing the likelihood that hair loss can be reversed.

Norwood Scale: A scale for the classification of hair loss.

Papilla: The small root area at the base of hair, which receives the nutrients needed for hair growth.

Placebo: A pill, topical cream, or injection made to appear exactly like a test medication, but without any of its active ingredients.

Polysorbate 80: An emulsifying agent that has been marketed extensively by “private” companies as a hair growth promoting agent.

Postauricular Flap: Surgical procedure that takes hair-bearing scalp from the area behind the ear and rotates it 90 degrees to the front, forming a hairline.