Hair Loss: Glossary
Biopsy: Piece of tissue cut out for microscopic
Bonding: A term used to describe the simple act of gluing a
hairpiece onto the scalp.
Catagen: The intermittent stage between the growing
(anagen) and resting (telogen) phases of the hair's growth cycle.
Chemotherapy: Chemical treatment, usually of cancers, using
drugs that have high levels of toxicity, frequently causing temporary
Club Hair: A hair that has stopped growing or is no longer
in the anagen phase. It is anchored to the skin with its "club-like" root, but
will eventually be pushed out and replaced by a growing hair.
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
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.