A topical anti-androgen that works by blocking the enzyme 5α-reductase.



The medical term for hair loss. There are numerous types of alopecia. Alopecia can be classified as diffused or localized, and by presence or absence of scarring. The most common form of surgically treatable alopecia is androgenic alopecia (AGA).


Alopecia Areata

A common non-scarring alopecia. Although the exact pathophysiology of AA is not clear, it is known that AA is a T-lymphocyte mediated autoimmune condition that occurs in genetically susceptible individuals It typically presents with sharply demarcated coin-sized patches of alopecia. The scalp is the most commonly affected area but any hair-bearing area can be involved. Spontaneous remissions and reoccurrences are common. Available treatment options are neither curative nor preventative.


Alopecia Reduction

A procedure that involves the removal of a strip of balding upper scalp in the crown and vertex areas. The natural flexibility of the scalp is used to stretch the surrounding hairy scalp into place.


Alopecia Totalis

Loss of all the hair on the scalp


Acne Keloidalis Nuchae

A chronic scarring folliculitis that mainly affects young black men. The lesions are localized on the neck and occipital scalp. It can be treated with corticosteroids either alone or in combination with antibiotics. Surgery is the treatment of choice in patients with very extensive keloidal plaque. Hair transplantation is not recommended


Alopecia Universalis

Loss of all hair on the body






A vasodilatator chemically similar to minoxidil. Studies providing evidence for its efficacy are missing. Claims are made that on deduction of telogen hair with anagens, inducible activity and prolonged hair follicle age occur.



The active growing phase of the hair that lasts between 2 and 6 years. An increase in the duration of anagen does not alter hair fiber density over the scalp; instead, it determines to what length the hair can grow. Anagen can be shortened in androgenetic alopecia.


5α –reductase enzyme

The enzyme that converts testosterone to the potent androgen dihydrotestosterone (DHT). It exists as two isozymes: type I and type II. Although the tissue distribution of the isozymes does vary, both are found in scalp follicles.


Anagen Effluvium

An abrupt hair shedding caused by interruption of hair growth. It follows administration of anti-cancer chemotherapeutic agents, radiation treatments, and various chemicals. Anagen effluvium results in hair breakage beginning at 2–6 weeks after exposure to the toxin.


Anchor System of the FollicularUnits

This defines the structures that impede the extraction of the follicular group from the surrounding tissue. The follicular adherence includes the sebaceous gland, and the insertion of the arrector pili muscle, the attachment of the dermis, and the connections between the connective tissue sheath and the surrounding adipose tissue.



Any natural or synthetic compound that stimulates or controls the development and maintenance of male characteristics.



An agent that blocks the action of androgens.


Androgenic Alopecia (AGA)

The AGA is a heritable, androgen and age-dependent process resulting in the progressive decline in visible scalp hair density in a sex-dependent defined pattern.


Anterior Temporal Fringe

The anterior border of the temporal area hair that falls inferiorly and vertically from the most posterior limits of the fronto-temporal recessions to a point approximately level with the external auditory meatus.


Arrector Pili Muscle

A tiny smooth muscle that connects the hair follicle with the dermis.


ARTAS System

A robotic FUE device that uses a two-step process. This is an “automated”system that evaluates follicular unit density, hair angle, and proper depths of sharp and unsharpenedpunch insertion based on the physician input data. Grafts are harvested while using a tension device. The graft is then removed with a pair of forceps.





A piece of tissue cut out of the body for microscopic examination.

Body Hair Transplant

Donor follicles are harvested from any region of the body except the traditional scalp donor area. Body hair includes all hair inferior to and inclusive of the neck and beard. Body hair has an unpredictable and variable yield.



Lowermost portion of the hair follicle containing rapidly proliferating matrix cells that produce the hair.



Convex protrusion of the outer root sheath in the most distal permanent

hair follicle stem cells.







Calculated Density

It is average number of hairs in each follicular unit. It is determined by dividing the number of hairs present in 1cm2 by the number of follicular units observed in the same cm2.


Camouflaging agents reduce the color contrast between hair color and the color of the scalp. They produce an overall perception of increased hair density. Hair fibers, powder cakes, scalp lotions, scalp sprays, and hair crayons are scalp camouflaging agents.



A brief transitional phase between anagen and telogen lasting only a few weeks.


Central Centrifugal Cicatricial Alopecia (follicular degeneration syndrome)

A form of scarring alopecia. It mostly affects African-American females. Hair loss usually begins at the vertex and expands outward symmetrically, eventually affecting the entire scalp. The cause of CCCA remains unclear. Topical corticosteroids and

immunomodulators, oral antibiotics, intra-lesional injections of corticosteroids, and short courses of oral corticosteroids are available options for patients


Christmas Tree Pattern

Frontal midline recession with thinning and widening of the central part of the scalp without diffused hair loss.


Cicatricial Alopecias (syn. scarring alopecias)

Uncommon and clinically diverse disorders that result in permanent and irreversible loss of scalp hair. These disorders may be primary, with the follicle itself being the target of the disease process, or secondary, where hair follicles are destroyed as part of amore generalized tissue-damaging event (e.g. deep skin infection, thermal burn, trauma, or ionizing radiation). Clinically it is characterized by the disappearance of visible follicular ostia within an area of alopecia.



An appearance of the scalp that occurs due to the dense placement of the graft relative to the surrounding scalp.


Cohen Hair Loss Index

Adapts to an infinite number of density and distribution patterns (male and female) and uses numbers instead of words to identify the topography of the scalp. Hair loss is scored with a single number from 1 to 100 and designated the hair loss index. The distribution of hair loss is displayed on a simple bar graph and called the hair loss profile.


Coverage Value – Dr. Koray Erdogan

A mathematical calculation developed as an objective method to standardize scientific criteria for calculating coverage through two components; density and thickness. This criteria addresses not only overall coverage, but also creates a standard for avoiding donor depletion by the multiplication of the number of hairs in a given area of the scalp by the hair’s thickness.


Coverage Value Exel Table – Dr. Jose Lorenzo

A mathematical table used to calculate Coverage Value in various scalp areas using Dr. Koray Erdogan’s mathematical Coverage Value Calculation.

Crown Area

An area in the top/back portion of the head that contains a swirl or spiral pattern of hair growth. Also called the vertex.


Cyproterone Acetate

An androgen receptor antagonist and progestin that should only be used in women.



The outermost layer of the hair shaft.




Densitometer (Trichoscope)

A tool that gives a rapid, accurate, and reproducible assessment of donor hair density.



The number of hairs in a specific area.





Dense Packing

There is no established definition of dense packing. For many surgeons, dense packing is defined as placing hair grafts at a rate higher than 30 grafts per square centimeter in the recipient area. Forty to 50 grafts per square centimeter are fairly common. The aim is to produce a more even, consistent, and natural looking hair.



Easy to apply compact powder that is used to conceal and cover up hair loss or thinning hair.


Dermal Papilla

A condensate of specialized mesenchymal cells with important inductive properties. It is situated at the base of the hair follicle. The dermal papilla contains nerves and blood vessels that supply glucose for energy and amino acids to make keratin. The dermal papilla determines the size of the hair bulb and the hair shaft produced; it is likely the target of androgen-mediated events leading to miniaturizations and hair-cycle changes.



An inflammatory condition of the skin.


Dermis (corium)

One of the two layers of skin. The outer layer is the epidermis and inner layer is the dermis. It is a supportive, compressible and elastic connective tissue protecting the epidermis, its appendages and the vascular and nervous plexuses running through it. It consists of cells, fibrous molecules and a ground substance.


Depth Control

Refers to the utilization of different accessories on or around the punch to precisely control the depth to which the punch can be inserted.


Diffused Patterned Alopecia (DPA)

A term used to describe diffused hair loss that involves thinning. The occipital donor area is spared.


Diffused Unpatterned Alopecia (DUPA)

A term used to describe general thinning across the entire scalp.


Dihydrotestosterone (DHT)

Dihydrotestosterone (DHT) is the most potent natural androgen in humans. Testosterone is converted to DHT by the enzyme 5-alpha reductase. It is thought that DHT is the key androgen required for the induction of MAG.


Discoid Lupus Erythematosus (chronic cutaneous lupus erythematosus) (DLE)

Discoid lupus is an auto-immune disease limited to the skin. DLE often leads to local areas of scarring and permanent localized hair loss. First-line treatment options include topical and intra-lesional steroids, hydroxychloroquine, and sun protection.


Donor Area

The fringe above the ears and around the back of the head where hair follicles are genetically programmed to remain intact and grow throughout life.


Donor Density

The number of hair in the donor area measured per square centimeter. In general, patients require a donor density of at least 40 FU/cm2 to be considered for transplants.


Donor Dominance



Donor Tension or Traction

Tension may be applied to the donor area to stabilize the fluidity of the tissue. Tension may be applied by a variety of means including the following: tumescence, clamps, or manual or stretching forces applied through other means such as tensioners or stapling a latex material from one side of the scalp to the other.


Drug Induced Alopecia

Drug-induced alopecia usually presents as a diffuse, non-scarring alopecia most commonly involving the scalp. In almost all cases there is recovery of hair loss after discontinuation of the medication.


Dull Dissection

When an unsharpened punch is inserted along the course of the follicle to facilitate its extraction.



Dutasteride inhibits both type I and type II 5α-reductase and was approved by the FDA for the treatment of benign prostatic hyperplasia. Dutasteride has been shown to significantly increase hair counts and hair weight, improve the ratio of anagen and telogen hairs, and improve scalp coverage.





The abnormal accumulation of fluid in the space between tissues.



Active hair loss denoted by a hair loss of > 100 hairs daily over a longer time period (2– 4 weeks)



The outer protective, non-vascular layer of the skin.


External Dissection

This action details how a graft is divided under the microscope into singles or groups containing fewer follicles than the original intact group, for example, to be used in or near the front hairline.



The release of telogen fibers from hair follicles.




Female Pattern Baldness

Female pattern hair loss (FPHL) is the most common cause of alopecia in women. It presents with diffuse non-scarring loss of hair, with prominent thinning over the frontal, central, and parietal scalp. The frontal hairline is characteristically retained.  The relationship between FPHL etiology and androgen or androgen receptor (AR) is less clear. The efforts to treat FPHL have mixed success and do not accomplish complete regrowth. Hair transplant surgery is emerging as an important option for patients with FPHL.


Finasteride is a potent and highly selective inhibitor of 5α-reductase type 2. It was developed for treatment of benign prostate hyperplasia, and in 1993 it was registered in the United States for the treatment of mild to moderate MPHL.  It reduces the conversion of testosterone to DHT. Finasteride prevents or slows the progression of MPHL, and about two-thirds experience some improvement.



Topical fluridil blocks AR in the hair follicles. Fluridil has been widely used in Europe, but is still awaiting FDA approval. It has been found to be safe for the treatment of pattern hair loss in men and women.


Follicular Cell Implantation/ Cell Therapy

In follicular cell implantation (FCI), dermal papilla cells are taken from a few follicles and expanded in culture and then implanted into the skin to induce the formation of many new follicles. In the future, FCI will offer a relatively minimally invasive treatment option for hair loss


Follicular Degeneration Syndrome

(See Central Centrifugal Cicatricial Alopecia)


Follicle Distortion

The physical movement of the follicle in reaction to the forces resulting from the physical process of follicular unit extraction.


Folliculitis Decalvans

A form of scarring alopecia that can present in the vertex area. It predominantly occurs in young and middle-aged adults. The exact cause is unknown. It can be very aggressive and resistant to therapy. Treatment involves topical and oral antibiotics as well as the anti-neutrophilic agent dapsone.


Follicular Density

Follicular density refers to the number of follicular units per square centimeter.


Follicular Group (Follicular Family, Follicular Cluster, Follicular Bundle)

These are defined as clusters of hair in the scalp that exit the skin in close proximity to each other and are separated by a gap from other clusters of hair.  The follicular group may consist of more than one follicular unit in a tightly packed distribution on the surface of the skin.


Follicular Pairing

The placing of two follicular unit grafts into one recipient site.


Follicular Unit

The majority of human hair shafts emerge from the scalp as single, double, and triple-hair groupings. This is the visible superficial portion of a distinctive histologic structure known as the follicular unit. The follicular unit consists of one to four, and occasionally five, terminal hair follicles, one, or rarely two vellus follicles, the associated sebaceous lobules, the insertions of the arrector pili muscles, its neural and vascular plexuses, and the fine adventitial collagen, which surrounds and defines the unit.


Follicular Unit Dissection

A technique in which naturally occurring, individual follicular units are dissected from donor tissue that has been removed as a single strip. Stereo-microscopic dissection is required.


Follicular Unit Extraction (FUE)

Follicular unit extraction (FUE) is a method of graft harvest whereby punches of various types are used to remove follicular units from the donor region one at a time.


Follicular Unit Graft

A graft consisting of a single follicular unit.


Follicular Unit Micrografting



Frontal Area 

An area that lies between the anterior hairline and a line initially drawn vertically from the left and right tragus and then gently curved anteriorly.


Frontal Fibrosing Alopecia

Generally accepted as a variant of lichen planopilaris. It presents with a recession of the hairline along the sideburns and central scalp. It also affects the eyebrows. It is more common in postmenopausal women. The treatment involves the use of topical, intra-lesional, and systemic anti-inflammatory treatments.


Frontal Forelock

A natural (or transplanted) zone of hair in the anterior aspect of the scalp which is separated from the adjacent fringe hair by an alley of alopecia or thinning hair.


Fronto-Temporal Recession

The non-hair bearing skin that lies between the superior antero-temporal hairline and the lateral border of the frontal hairline


Frontal Tuft

The relatively narrow zone of hair that juts out from the posterior aspect of the frontal area or a mid-parietal bridge and has on each side a wide and deep fronto-temporal recession.


FUT (Follicular Unit Transplantation)

A method of hair restoration surgery whereby parallel incisions are made in the donor scalp area to remove a strip. The length and width of the excision depend on the amount of grafts. From this strip, individual follicular units are then dissected under the stereo microscope.





The layer of the scalp that lies in between the subcutaneous tissue and the loose connective tissue.


Graft Calculator – Dr. Koray Erdogan

A downloadable application used to manage calculated density during surgery and adjust punch sizes accordingly to meet the determined Coverage Value.

Graft Planting

Numerous techniques and instruments are available for graft placement. The fundamental principles of this aspect of the procedure include gentle grasping of the grafts, maintenance of graft hydration, placement of grafts in the identical angle of site creation, and also maintaining appropriate rotation of the natural curvature of the hair graft.





Hair itself has few physical functions. These include defense against the effects of UV radiation, suppression of heat loss, and tactile sensation. The various hair types consist of terminal, intermediate, and vellus hairs. Hair has two separate structures: the follicle in the skin and the hair shaft, which is visible on the body surface.


Hair Additions

Any external hair bearing device added to existing hair or scalp to give one the appearance of a fuller head of hair, i.e. hair weaves, hair extensions, hair pieces, toupees, non-surgical hair replacements, partial hair prostheses, hair wefts, etc. Devices may consist of human hair, synthetic fiber or a combination of both.


Hair Canal

Tubular connection between the epidermal surface and the most distal part of the inner root sheath. Contains the hair shaft.



An instrument designed to precisely and accurately measure hair loss, growth and breakage on any area of the scalp. It gives reproducible cross-sectional trichometry measurements. Benefits of using the device include assessing the stability of hair loss in patients, quantifying their improvement in density over time, and also using a measuring device in clinical trials.


Hair Coverage

Hair coverage is the combination of hair follicle density per unit area of skin with the average hair fiber thickness. Improvements in both terminal hair density and average hair diameter work synergistically.


Hair cycle

Hair follicles undergo a growth cycle. The cyclic activity of the hair follicle requires the regeneration and new assembly of its non-permanent portion during each new hair cycle. On average, the amount of new scalp hair formation matches the amount that is shed, thereby maintaining a consistent covering. Changes in hair growth cycling elicit a hair disorder There are 3 main phases of the hair follicle cycle: an active growth phase called anagen; a catagen phase when the hair follicle regresses; and a telogen phase when the hair follicle is largely quiescent. The two other stages of the hair cycle have been described as exogen (the release of telogen fibers from hair follicles) and kenogen (the lag time between the exogen and new anagen fiber development). How long each phase takes partly depends on the type of hair follicle involved and its geographic location.


Hair density

A product of the concentration of hairs and the size or caliber of each individual hair.



The HairDX test is the first genetic test for predicting the risk of pattern hair loss.


Hair Economics



Hair Fiber

The most visible product of the hair follicle. It is formed of keratin proteins,


Hair Flaps



Hair Follicle



Hair Follicle Anatomy

The hair follicle can be divided into three anatomical compartments: the infundibulum, isthmus, and the inferior segment. The upper follicle is permanent, whereas the lower follicle, the inferior segment, regenerates with each hair follicle cycle. The infundibulum extends from the skin surface to the sebaceous duct. The isthmus, the permanent middle portion, extends from the duct of sebaceous gland to the exertion of arrector pilli muscle. The inferior segment consists of the suprabulbar area and the hair bulb. The hair bulb consists of extensively proliferating keratinocytes and pigment-producing melanocytes of the hair matrix that surround the pear-shaped dermal papilla that contains specialized fibroblast-type cells embedded in an extracellular matrix and is separated from the keratinocytes by a basement membrane. The hair matrix keratinocytes move upwards and differentiate into the hair shaft, as well as into the inner root sheath; the melanocytes transfer pigment into the developing hair keratinocytes to give the hair its color. The epithelial portion of the hair follicle is separated from the surrounding dermis by the perifollicular connective tissue or dermal sheath. This consists of an inner basement membrane called the hyaline or glassy membrane and an outer connective tissue sheath. The major compartments of the hair follicle from the innermost to the outermost include the hair shaft, the inner root sheath, the outer root sheath, and the connective tissue sheath

Hair Grafts




The hairline is a prominent part of the largest visible feature of the face. Creating a natural hairline is one of the most important elements of a successful hair transplant. The goal is to achieve the age-appropriate look that will sustain a natural appearance with the future progression of hair loss.


Hair-Mass Index

A measurement of hair density that incorporates both the number of hairs per square centimeter and the hair shaft diameter.


Hair Mass

A quantity that reflects the cross-sectional area of all hairs that emerge from 1cm2 of the scalp surface.

Hair Mount

Hair mount is the method for assessing the hair bulbs and shafts using light microscopy.


Hair Plugs



Hairline Refinement (Hairline Correction)

Refers to the use of a variety of newer, more delicate grafting techniques to alter, camouflage or soften the results of older hair transplant techniques.


Hair Shaft

The hair shaft is the part of the hair follicle that exits the epidermis. It consists three layers: medulla, cortex, and cuticle.


Hair System

Custom-made real hair to cover the entire scalp.


Hair Transplant

A surgical technique that transfers hair follicles from the donor area to the recipient area. The hair transplantation process consists of two parts: 1) removing the donor follicles, and 2) placing them back into the skin.



The term used to describe removing hair from the donor area. 



This is the name given to the loss of skin color caused by loss of melanin, loss of the hue from individual follicles, and the loss of circulation from the skin’s surface during the healing process. The surface area of hypopigmentation (commonly named white dots) can be extremely variable depending on different factors, such as skin or hair color, and the tools used for the extraction.





The protective response of the tissues of the body to irritation or injury.



Most proximal part of the hair follicle relative to the epidermis, extending from the sebaceous duct to the epidermal surface


Inner root sheath

A multi-layered, rigid tube composed of terminally differentiated hair follicle keratinocytes surrounded by the outer root sheath.



The mid part of the hair follicle extending from the sebaceous duct to the bulge.


In vitro

Occurring in laboratory apparatus.



Occurring in living organisms.




Juri Flap (temporo-parieto-occipital flap)  

A flap that is used to reconstruct the hairline and mid-scalp. The flap has fallen out of favor today.






K.E.E.P.  (Koray Erdogan Embedding Placer) – Dr. Koray Erdogan

A placing instrument developed as a dynamic response to; 1) low hair count regrowth rates (as opposed to graft regrowth rates) determined to be the result of graft curving and damage owing to the use of forceps during the graft placement phase of surgery, and 2) the need for an instrument used to place long hair grafts without damaging them.  



An overgrowth of scar tissue at the site of a skin wound.



Lag time between exogen and new anagen fiber development.



An anti-fungal agent. It is used topically for the treatment of seborrheic dermatitis and dandruff. It may stimulate hair growth. The mechanism may involve inhibition of inflammation or anti-androgenic properties of the agent.




Lateral Slit (perpendicular coronal) – Dr. Jerry Wong

Incisions made perpendicular to the direction of hair growth. The lateral slit technique gives the hair restoration surgeon the ability to control the angle, direction and orientation of transplanted hair.


Lanugo Hair

Fine hair on the body of the fetus, usually shed in utero or within weeks after birth.


Lichen planopilaris (LPP, follicular lichen planus of the scalp)

Lichen planopilaris is an autoimmune disorder that causes a scarring permanent alopecia. Adult women make up the majority of the LPP patient population. It is the most common form of primary cicatricial alopecia. It results in a shiny alopecia of the mid-scalp, vertex, or parietal areas. According to the severity of disease treatment options include corticosteroids, hydroxychloroquine and immunomodulating agents.


Loose Anagen Syndrome

No treatment is available for LAS.


Low-Level Light Therapy

Low-level light therapy (LLLT) is a technique used in the treatment of AGA. Several types of products using LLLT are available for the adjunctive treatment of AGA. LLLT, particularly 650–900 nm wavelength at 5 mW, may be an effective alternative treatment for AGA patients.


Liposomal Adenosine Triphosphate

Oxygen and glucose are required for the production of ATP, the cell's primary fuel. One method to replace graft oxygen needs that may not be fully met by the patients vascular beds is to use post-operative liposomal adenosine triphosphate (ATP). Use of liposomal ATP was shown to enhance graft survival and graft quality when used as an additive to the holding solution and as a postoperative spray.


Ludwig Scale

The scale for describing a type of female pattern hair loss in which there is centralized diffused loss of hair. A Ludwig I describes mild hair thinning throughout the central scalp. Ludwig II is moderate with notable thinning in the central scalp. Ludwig III shows severe hair loss and thinning in the central scalp.





A megasession refers to transplanting a large number of follicular unit grafts in a single session. Megasessions are capable of treating a significant area of the scalp in one session.



Melatonin is secreted by the pineal gland and regulates the sleep cycle. It has been known to modulate hair growth, pigmentation, and molting in many species including humans. Topical application of melatonin 0.1 % solution was shown to significantly increase anagen hair.



Mesotherapy consists of superficial scalp injections of pharmaceuticals and vitamin compounds that have been previously used to treat hair loss via the topical or systemic routes of administration.


Mid-scalp (Top)

Lies immediately posterior to the front and extends to the vertex (crown). It is bound laterally by the temporal/parietal fringes.



The primary pathological process in androgenetic alopecia, resulting in the conversion of large (terminal) hairs into small (vellus) hairs. Miniaturized follicles still have the capacity to produce hairs and retain cycling ability.





Multi-Unit Grafts (MUG)

Grafts that contain two or more follicular units in a single graft. This term replaces the older minigraft. In practice today, MUGs contain 2-6 follicular units per graft.


Multi-Unit Grafting




Minoxidil was originally developed as an antihypertensive agent. It was approved by the FDA for treatment of MPHL as 2% and 5% scalp lotion. The mechanism of action of minoxidil on hair growth is still unclear. Recent studies suggest that it also enhances hair growth by increasing the production of prostaglandin E2. Topically applied minoxidil increases hair weight with a less dramatic increase in hair counts. Adverse effects of minoxidil include skin irritation, hypertrichosis on the face and hands, and tachycardia.





Nanofibers  consist of ultra-fine microfiber hair camouflage products made entirely of natural keratin. It works by binding electrostatically charged microscopic hair fibers to each of the individual hairs to create a fuller looking head of hair.


Norwood Classification

The Norwood–Hamilton Classification is widely used to determine the extent of hair loss. Class I represents adolescent or juvenile hairline without evidence of balding. Class II shows some limited fronto-temporal recession and mild elevation of about a finger’s breadth above the upper brow crease. This does not represent any balding, but is part of a normal progression for an adult. Class III is the earliest stage of androgenetic alopecia with a deeper fronto-temporal recession. Class III vertex is a variation in which there is early signs of hair loss in the vertex. Class IV shows further fronto-temporal hair loss and recession with vertex loss as well. There is a strong band of hair that still separates the front from the back. Class V shows more enlarged area of hair loss in which the band between the front and the vertex begins to break down. Class VI shows the loss of the band connecting the front and the vertex but with still a high fringe of hair maintained. Class VII shows a low fringe with just a low horseshoe of hair left.




Occipital Fringe

The superior border of the occipital area of permanent hair that surrounds the alopecic or thinning vertex.


Oscillating Extraction

A process whereby the punch is rotated back and forth through different arcs and repetitions per minute (RPMs) during penetration. This may be done by hand or by motor.


Outer Root Sheath

The outermost layer of the hair follicle. Merges proximally with the inter-follicular epidermis and distally with the hair bulb.




Parietal Fringe

The superior border of permanent parietal area of hair that extends posteriorly from a line drawn vertically from the tragus to the beginning of the occipital fringe.


Partial Follicular Family Harvesting (vertically split harvesting)

This involves the entire process of harvesting a fraction of a follicular unit such that one portion of the follicular unit is harvested from the donor area while the other portion of the follicular unit remainsin the donor area.


Pilosebaceous Unit

The term pilosebaceous unit describes the integrated structure of the hair follicle, hair shaft, adjoining arrector pili muscle and associated sebaceous gland.



A situation whereby the skin surface of the graft appears lower than the surrounding skin.



An inactive substance prescribed as if it were effective dose of a needed medication.


Placebo Effect

A physical or emotional change occurring after a substance is taken or administered that is not the result of any special property of the substance.


Polytrichia (tufting)

With cicatricial alopecia the scarring that occurs obliterates follicular ostia and causes remaining ostia to coalesce so that several follicles emerge out of one site.


Platelet-Rich Plasma (PRP)

An autologous preparation of plasma with platelets that are capable of secreting growth factors and cytokines that stimulate stem cells. Some hair transplant surgeons have used PRP in hair transplantation procedures either by storing the grafts in PRP until they are placed on the scalp, or by injecting PRP into the scalp prior to placement of grafts. The results of studies on the use of PRP as an adjunctive modality in hair transplantation remain controversial.



When one or more than one terminal hairs removed by pulling out a follicular group with a forceps with the aim of the removal of viable follicles from the donor area that can be inserted in the recipient area .


Primary Cicatricial Alopecias

Primary cicatricial alopecias refer to a group of rare, idiopathic, inflammatory scalp disorders that result in permanent hair loss. Cicatricial alopecias are traditionally classified by their inflammatory infiltrate (lymphocytic, neutrophilic, mixed). The inflammatory process affects mainly the upper portion of the follicle and is followed by a permanent destruction of the hair follicle. Primary cicatricial alopecia frequently starts at the central and parietal scalp before progressing to other sites of the scalp. A lack of follicular ostia is the hallmark of scaring alopecia. A thorough examination of the entire scalp, a detailed clinical history, and 1 or 2 biopsy samples of an active lesion are crucial in the diagnosis of cicatricial alopecia. The goal of any therapy is the arrest of further loss. Hair transplantation and scalp reduction surgery are possible once the lesions are burnt out and stable. Graft survival may not be as good as in androgenetic alopecia and disease reactivation is possible at any time after surgery.



Prostaglandins are potent bioactive lipid messengers. They cause many physiological responses.


Prostaglandin Analogs

The prostaglandin (PG) pathway is related to hair growth because PGE2 and PGF2α promote hair growth, whereas PGD2 inhibits hair growth in both mice and human follicles. The potential role of prostaglandin analogs in the treatment of alopecia was noted after the lengthening of eyelashes and eyebrows was observed when they were used topically for glaucoma.


Pseudopelade of Brocq

A chronic asymptomatic primary cicatricial alopecia most often involving the vertex. It is non-inflammatory. The classic appearance of pseudopelade is the so-called footprints in the snow. Potent corticosteroids, hydroxy-chloroquine, and thalidomide have all been used.


Pull Test

The hair pull test is a simple diagnostic test that can be performed to determine the severity and the location of the hair loss Results can vary depending when the hair was last shampooed and combed. Approximately 50- 60 hairs are grasped between the thumb, index and middle fingers from the base of the hairs near the scalp and firmly but not forcefully tugged. If more than 10% or 6 hairs are pulled away from the scalp, this constitutes a positive pull test, which implies active hair shedding



This is defined as the anterior traction used for the removal of the graft, after it has been punched. Grafts may be pulled with a one-hand pull with a single forceps, a two-hand pull with two forceps or with suction.



A surgical instrument used to obtain small samples of tissue.


Punch Grafting

Punch grafting refers to removal of hair grafts using a round punch of various sizes.




Recipient Area

Area where hair loss has occurred and hair follicles will be implanted during a hair transplant procedure. There are many methods of creating recipient sites, including lightning blades, sapphire blades, custom-cut razor blades, and various needles.


Recipient Dominance

Recipient dominance refers to the influence of the recipient site scalp on the growth of transplanted hairs.


Rotating Extraction

The punch is rotated a full repetitive 360-degree cycle during penetration of the skin. This is usually done by motor.


Rotating and Oscillating Extraction

When rotation followed by oscillation is employed during the penetration of the punch. Rotational speed, arc of rotation, ramp (amplitude from starting position to ending position) of rotation, ramp of arc, and duration of each individual cycle may be controlled.


Round Graft

The first type of graft used in hair transplantation. The round graft is obtained from the donor site by surgical removal and may be used as is or may be sliced into smaller sections for micro, mini or slit grafts.



Sagittal Incisions (parallel)

Incisions made parallel to the direction of hair growth.


Saw Palmetto (serenoa repens)

It is an over-the- counter herb that is believed to inhinit 5-a reductase conversion of testosterone to DHT.


Scalp Biopsy

In any patient where there is diagnostic uncertainty and where therapeutic options will be altered by an accurate diagnosis, a biopsy should be performed. Scalp conditions that usually require biopsy include all forms of scarring alopecia.


Scalp Extension 

A process for alopecia reduction (AR) developed in order to minimize the unfavorable stretch back of reduced bald scalp following AR.


Scalp Micro-pigmentation

A medical tattoo application for balding or thinning hair.


Scalp Reduction

A procedure that removes the bald scalp and brings the edges of hair-bearing scalp closer together. Scalp reduction is now seldom performed as the primary surgical treatment for alopecia.


Scalp Rotation Flaps




This is a superficial cutting of the epidermis and dermis with a punch to produce a superficial circumferential or semi-circle incision around a follicular grouping.


Sebaceous Gland

A gland localized close to the insertion of the arrector pili muscle. It secretes sebum to the epidermal surface.


Seborrheic Dermatitis

An inflammatory condition of the skin most commonly occurring on the scalp, face, and chest. The term dandruff or pityriasis capitis corresponds to a milder form of seborrheic dermatitis. It is thought to result from a combination of factors. Clinical features can range from fine scaling of the scalp to erythematous patches. It is a relapsing condition that may require maintenance treatment. Anti-dandruff shampoos are readily available and effective in most cases. Common active ingredients include selenium sulfide, zinc pyrithione, ketoconazole, miconazole, and ciclopirox. Tar-based shampoos are also effective.


Senile Alopecia (senescent alopecia)

Hair loss that naturally occurs with age. It is described as a diffused thinning involving the whole scalp due to a steady decrease in thick terminal hairs. It is not clear whether this is distinct from androgenetic alopecia or is simply a continuation of it in later life.


Sentinel Hairs

Sentinel hairs refer to the very fine single hairs that scattered in front of the hairline to soften the appearance of the hairline.


Slivers and Slivering

Dividing the donor strip into sections (or slivers) of variable widths according to the desired graft size called as slivering. The slivering technique has been compared to slicing a loaf of bread,” an analogy in which the loaf is the strip and the emerging slices are the slivers. Creating the ideal sliver without transection is the most difficult step in graft preparation. The use of magnification equipment is essential for the creation of slivers.


Sharp Dissection

This is when a sharp punch is inserted along the course of the follicle to facilitate its extraction.


Slit Graft



Slit Creation

Creating slits over the recipient area. Important considerations include slit size, depth of incision and angle, and direction.



This is the action of separating with the punch in vivo (or in situ) a portion of the follicles from a group (follicular family or follicular unit).


Strip harvesting

This is a technique for harvesting donor hair. It involves excising a horizontal section of safe donor hair from the occipital, parietal and occasionally temporal regions. The resulting wound is sutured or stapled and leaves a linear scar.



Spironolactone is an aldosterone antagonist employed in clinical practice as a potassium-sparing diuretic. It reduces adrenal androgen production and exerts competitive blockade on androgen receptors in target tissues. This medication has been used off-label in female pattern hair loss. These types of medications that bear systemic anti-androgen effects are contraindicated in men. They should not be used during pregnancy due to their teratogenic effects.



This describes the divergence of follicles from one another, typically occurring at the lower one-third of the follicular unit.

Stem Cell

Stem cells reside in rather undifferentiated, quiescent states and form precursors, transient amplifying cells, which provide further proliferation and differentiation into the different cell types. Hair follicle stem cells are multi-potent, capable of proliferation and able to give rise to all cell types of the hair, the epidermis and the sebaceous gland.


Sequential Method (DES) - Dr. Koray Erdogan

The surgeon holds the punch and the forceps in both hands at the same time. The grafts are first cut with the punch in one hand and then removed with the forceps held in the other hand, one graft at a time and in rapid sequence


Step Methods

These methods relate the steps that need to be applied with a punch or other cutting tool to release the graft from the surrounding tissue. All methods take a last final step common to all the techniques; the collection of the follicle with forceps or suction.


Sub- Follicular Group Graft

This is a graft extracted from a follicular group whereby a portion of the follicular group remains in the donor area.


Superior Temporal Fringe

This is the border of hair that extends from the fronto-temporal point to a point that lies straight up from the external ear meatus.





The resting stage of the hair cycle. Club hair is the final product and is eventually shed. The telogen stage typically lasts for two to three months before the scalp follicles re-enter the anagen stage and the cycle is repeated.


Telogen Effluvium

Refers to excessive loss of telogen hairs due to an abnormality of hair cycling. It may occur in response to a number of triggers including fever, hemorrhage, severe illness, stress, and childbirth, crush dieting, iron deficiency. It typically occurs approximately 3 months from the time of the precipitating event.


Temples/Temporal Area



Temporal Point

The sharply angulated projection of hair at the anterior aspect of the temporal fringe. Temporal points can be classified into the following N = No thinning or recession of temporal point hair, T = Thinning and/or mild recession, P = Apex of recession is parallel to the anterior sideburn line, R = Recession has caused a reversed angle that is usually anteriorly convex, but is now concave. This classification uses letters N, T, P, and R, which are added in brackets after the usual Norwood classification to further define the patients current hair loss status. Classes P and R would benefit from transplantation.


Temporal Triangular Alopecia (TTA)  

TTA is a non-scarring, non-inflammatory alopecia on the fronto-temporal scalp. Lesions can be present at birth, but mostly develop in the second to sixth year of age. TTA seems to be unresponsive to medical treatment. However, few cases are reported on successful hair restoration surgery in TTA


Terminal Hair

Large, usually pigmented hairs with a diameter of greater than 0.06 mm and a length greater than 1 cm. The hair bulb is rooted deeply in the subcutaneous fat.



A term to describe the attachment of the connective tissue sheath and outer root sheath to the surrounding adipose of a follicle.


Tissue Expander

A reconstructive balloon-like device that can be used to enlarge the hair-bearing scalp on the sides of the head, providing a larger supply of hair with which to replace the bald areas. Often used in hair flap techniques and scalp reductions.


Tissue Extender

A device used to stretch the scalp. Often used to speed up the process of scalp reductions by stretching the sides of the scalp that contain hair to achieve rapid elimination of bald areas.



Keratin-based fibers that adhere to scalp and existing hair. It helps thicken the appearance of existing hairs and camouflage balding areas on the scalp. Toppik Hair Building Fibre magnetizes to the hair with static electricity and will stay in place until  the next shampoo.



A compulsion to pull or pluck one’s hair repetitively is called trichotillomania, and can result in unnatural or even bizarre patterns of hair loss. Trichotillomania usually occurs in adolescents during times of psychosocial stress. It usually presents with patches of alopecia with angulated and irregular borders and with broken hairs of different lengths, usually located on the fronto-temporal or fronto-parietal scalp opposite the dominant hand. Appropriate psycho-education and minimally invasive behavioral treatments are possible interventions for this common disorder. The medications such as opioid blockers, atypical neuroleptics, and glutamate modulators hold promise as treatment for trichotillomania. The presence of active trichotillomania is a contraindication to hair transplantation.


Tinea Capitis

A dermatophyte infection of the hair follicle and can be inflammatory or non-inflammatory.

Traction Alopecia

Traction alopecia is usually due to excessive stretching of hair shafts by hair-styling practices. Thinning and recession involve the frontal area, but may extend into the temporal regions Prolonged traction alopecia can scar the new hair follicle and cause permanent hair loss. Hair transplantation is successful in lowering the receded frontal hairline and re-establishing appropriate density.



A term used to reportany microscopically visible breakage of a follicle anywherealong its entire length. A graft could be a completely transected graft when all of the follicles are cut transversally or a partially transected graft when one or more follicles are cut leaving one or more intact follicle.


Triangular Alopecia (congenital triangular alopecia, temporal triangular alopecia)

Triangular alopecia is a relatively uncommon condition usually detected in early childhood. Hair loss presents near the fronto-temporal point, in a triangular pattern, with the base of the triangle directed anteriorly. The area may be entirely hairless or have small vellus hairs scattered throughout. Triangular alopecia is amenable to hair transplantation, and excellent cosmetic results can be achieved.



Trichoscopy is the dermatoscopy of the hair and scalp. It can be performed with a handheld dermatoscope or a digital videodermatoscopy system. It may be applied in differential diagnosis of multiple hair and scalp diseases


Trichophytic Closure

A type of closure of the donor scalp. The term trichophytic (i.e., promoting hair growth) is used to describe various techniques in manipulating the donor site wound with the goal of having at least some hair grow through the scar to diminish its visibility.



This refers to the removal of the dermis and other undesired peri-follicular tissues of an graft under the microscope with the aim of making the graft slimmer.


Tug Test

The tug test is a simple clinical test that is used to show hair fiber fragility. With one hand, a group of hairs is held while the other hand pulls away the distal ends. Any hair breakage is considered abnormal and is a sign of hair fragility.



The area to add rigidity and create a more stable platform for the procedure.




Vellus Hairs

Small, soft hairs with a diameter less than 0.03 mm and a length less than 1 cm. They have no pigmentation.

Vertex (crown)

The most posterior area of male pattern baldness that is characterized by a whorl arrangement of the hair direction. It extends from the posterior border of the mid-scalp to the posterior curved parieto-occipital fringe of hair.


Vertex Transition Point

The most posterior point of the top or mid-scalp that generally lies just behind the highest part of the skull. It is the approximate point where the hair changes direction from a predominantly anterior, or radially anterior direction, to a whorl.





A whorl describes the circular spiral pattern that exists in the vertex.



Signaling is critical for hair follicle growth and components of this pathway are required in the induction of hair recycling. The presence of WNT agonists and antagonists is likely to lead to the appropriate balance of WNT activity in actively growing and cycling hair follicles.





Zinc is crucial for enzyme functioning. Zinc deficiency is also associated with alopecia.