Hair Transplant Glossary of Terms
The medical term for hair loss without specifying what type of hair loss.
A medical condition in which circular patches of hair loss can occur in hair-bearing areas with the first episode occurring 60% of the time before the age of 20. The cause of alopecia areata (AA) is unclear and can be partly genetic or other factors. The mechanism by which AA occurs is a T-cell mediated immune attack of the hair follicle. The area of alopecia areata may remain or resolve itself over time with or without intervention. For limited cases of AA, intralesional steroid injections and minoxidil (See Minoxidil) are ideal treatments. For more extensive loss, topical immune modulators may be necessary in cases in which all scalp hair is gone (alopecia totalis) and eyebrow/eyelash/body hair is also gone (alopecia universalis). AA can also be classified as to the pattern of loss such as classic alopecia areata that occurs as circular patchy loss is known as alopecia areata circumscripta. A loss of hair around the back of the head in the occipital region that appears as a ring of complete hair loss is known as ophiasis. The exact opposite type of loss in which the frontal, temporal and parietal regions lose hair, which is quite rare, can also occur and is known as sisypho or reverse ophiasis. Sisypho can mimic male pattern baldness, or androgenetic alopecia (See Androgenetic Alopecia). One should still be able to see the follicular ostia (the openings of lost follicles on the scalp) unlike in scarring alopecias (See Cicatricial Alopecia) and in the active periphery one can see exclamation point hairs in which the broken distal hair is thicker than the proximal hair shaft. Hair transplantation into active areas of AA is not advisable, as the rate of hair growth in these patches are in general very poor.
Formerly called scalp reduction, alopecia reduction (AR) is a type of surgery for hair loss in which the bald areas of the crown and at times the midscalp are removed classically in a vertical incision (but can be horizontal, Y-shaped, etc.) and closed and must be performed in a sequential fashion. Scalp extension (See Scalp extension) can reduce the number of sessions and the interval between ARs and is a type of AR developed by Patrick Frechet. AR can be combined with traditional hair transplant surgery in the frontal region or “U-shaped” region.
A type of alopecia areata in which all of the scalp hair is lost. See Alopecia Areata.
A type of alopecia areata in which all the scalp hair, eyebrow, eyelash, and body hair is lost. See Alopecia Areata.
The growth phase of the hair cycle that typically occupies about 90% of the time and spans from 3 to 4 years. The other two phases of the hair cycle are catagen (See Catagen) and telogen (See Telogen). Anagen can be shortened in androgenetic alopecia (See Androgenetic Alopecia).
The condition in which hair is lost during the anagen phase (See Anagen) in which hair shows both loss and abnormal breakage. Anti-neoplastic (anti-cancer) drugs, e.g., cisplatin, carboplatin, etc., that arrest active cell division can cause anagen effluvium during the sensitive and highly mitotic anagen phase of hair growth. The condition is generally reversible with the cessation of the anti-neoplastic medications.
Androgenetic Alopecia (AGA)
The term that describes male pattern baldness (MPB) and can be thought of as synonymous with MPB. The cause of AGA is polygenic, i.e., arises from multiple genes. Therefore, the old wives’ tale that looking at your mother’s father will dictate your hair loss is inaccurate. Typically, the process of AGA involves the conversion of terminal hairs (See Terminal Hairs) to fine vellus hairs (See Vellus Hairs) through a process known as minaturization as well as the conversion of anagen phase (See Anagen) more readily and more prevalently to the telogen phase (See Telogen). A normal ratio of anagen to telogen hairs is approximately 7:1, which can be changed to an unfavorable ratio of 2:1 in AGA. Women can also experience AGA if they exhibit the typical male pattern hair loss in which hair is recessed in the fronto-temporal region and/or vertex/crown region. The susceptible hairs that are lost in AGA are influenced by the local hormonal milieu with the increased presence of dihydrotestosterone (See Dihydrotestoterone), or DHT, which arises from the conversion of testosterone to DHT. Medications like finasteride (See Finasteride) can block the conversion of testosterone to DHT through an enzyme known as 5-alpha reductase Type II in order to minimize and reverse hair loss in susceptible hairs. Lower estrogen levels can also cause hair loss in both men and women as well as increased presence of androgen receptor proteins. AGA is progressive in nature throughout one’s lifetime.
Arrector Pili Muscle
The muscle that attaches to the bulge area of the hair shaft in the middle of the hair shaft length which is thought to be the area for stem cell regeneration of the hair shaft.
Body Hair Transplant
Body hair can be transplanted from the chest, arms, and legs to the central scalp in individuals who have depleted all of their existing occipital donor hair through numerous previous hair transplant sessions. Body hair transplants are not as reliable as scalp hair in terms of overall growth. Also, the coarser and shorter anagen phase of these types of hairs make them not ideal for hairline placement. However, over time a phenomenon known as recipient dominance (See Recipient Dominance) in which the influence of the recipient scalp can cause changes to the transplanted hair can make the body hair begin to grow longer (increased anagen phase) and finer like regular scalp hair. Body hair is extracted through a process known as follicular unit extraction or FUE (See Follicular Unite Extraction) rather than conventional strip harvesting used in harvesting scalp from the back of the head.
The basal part of the hair shaft that includes the dermal papilla (See Dermal Papilla) and the matrix (See Matrix) in which the hair shaft originates and grows. This lower part of the hair shaft is considered non-permanent and is regenerated during the hair cycle. The area immediately above the bulbar area, known as the suprabulbar area (See Suprabulbar Area) is also non-permanent.
The central region of the hair shaft that divides the permanent section of the hair (infundibulum and isthmus) from the lower non-permanent region (suprabulbar and bulbar) and is marked by the attachment of the arrector pili muscle. It is thought that the bulge area contains the stem cells that help regenerate the hair shaft. The bulge area like the upper hair shaft is also considered a permanent part of the hair shaft.
The term used to describe the ability of one’s hair to cover exposed and bald scalp through increased or sufficient hair density. Also, camouflage can refer to certain types of products that increase the visual density of the hair, e.g., Toppik (See Toppik), or the reflective surface and color of the scalp, e.g., DermMatch (See DermMatch).
The second phase of the hair cycle that follows the anagen growth phase (See Anagen). During this phase, the lower non-permanent portion of the hair shaft undergoes active destruction in which the formerly actively dividing matrix cells and keratinocytes of the outer root sheath of the bulbar region begin to undergo apoptosis (or cell death) and the dermal papilla (See Dermal Papilla) begins to retract from the deeper subcutaneous tissue to the level of the dermis. Hairs spend about 1% of the time in catagen compared with about 90% in anagen and 9% in telogen (See Telogen) in a non-balding scalp. Catagen typically lasts about 2 to 3 weeks following 3 to 4 years of anagen growth.
The descriptive term used by hair transplant surgeons to describe the region that falls right behind the hairline zone in the central and anterior location. The central forelock is considered an area of primary aesthetic importance when rebuilding the central and frontal regions of the scalp during hair restoration, as this area can provide a higher impact in visual density as compared with other regions of the scalp. The region that falls immediately behind the classical central forelock toward the midscalp that has been more recently recognized for its importance in creating visual density to the scalp during hair transplant.
Central Centrifugal Cicatricial Alopecia
This type of scarring alopecia describes disparate entities that arise in the vertex of the scalp and include folliculitis decalvans, follicular degeneration syndrome, and pseudopelade of Brocq (see Folliculitis Decalvans, Follicular Degeneration Syndrome, Pseudopelade of Brocq).
A type of hair loss that involves scarring and can be considered an emergency for treatment. The two major types of cicatricial alopecias are inflammatory that include discoid lupus, lichen planopilaris, and folliculitis decalvans (See Discoid Lupus, Lichen Planopilaris, and Folliculitis Decalvans) and non-inflammatory that include pseudopelade of Brocq and follicular degeneration syndrome (See Pseudopelade of Brocq and Follicular Degeneration Syndrome).
Christmas Tree Pattern
A pattern of female hair loss in which the hair loss appears to resemble a Christmas Tree when viewed from above with the apex of the tree situated posteriorly. This term was originally coined by Dr. Elise Olsen who postulates that approximately 80% of female pattern hair loss fits this description. Other physicians and surgeons may disagree with this high a prevalence. Other types of female pattern hair loss include Ludwig (See Ludwig Scale), general diffuse hair loss, and male pattern hair loss or androgenetic alopecia (See Androgenetic Alopecia).
Chronic Telogen Effluvium
A condition more prevalent in women between the ages of 30 and 60 years of age in which they shed hair periodically without an obvious definable cause through a process of telogen effluvium (See Telogen Effluvium).
A type of hair transplant technique practiced at times at the Lam Institute for Hair Restoration in the right surgical candidate that employs a combination of both follicular unit grafts (See Follicular Unit Grafts) and multiple unit grafts (See Multiple Unit Grafts) in order to achieve both a seamlessly natural result and unsurpassed hair density oftentimes in a single hair transplant session.
The cobblestoned appearance of the scalp that occurs due to placement of the graft too high relative to the surrounding scalp. This technical error can be corrected by slicing off the elevated scalp portion that appears abnormal. Superior hair restoration should avoid this type of error. The opposite problem is divoting or pitting (See Pitting) in which the graft is placed too deep relative to the surrounding scalp.
The unnatural appearing look to a hairline created by sweeping one’s temporal hair (See Temporal Hair) over the central scalp that may induce elevator eyes (See Elevator Eyes). The reason that a combover appears unnatural is that hair that falls outside of the outside part of the eye (lateral canthus) should fall away and down the sides of the head and not be directed over the central scalp and hairline.
In between the outer root sheath (ORS) and the inner rooth sheath (IRS) of the hair follicle lies the companion layer, which is a single layer of flattened cells. The companion layer acts a slippage plane to allow the IRS-sheathed hair shaft to move up in conjunction with Henle’s layer while the ORS remains stationery.
Placing grafts into a recipient site (See Recipient Site) that is too tight relative to the size of the graft leads to graft compression making the graft appear like a large single graft resembling a plug (See Plugs). Proper graft to recipient site fit is imperative in superior hair restoration.
Cyproterone acetate, an androgen receptor antagonist and progestin, should only be used in women, given the aforementioned risk of systemic feminization. Although of proven benefit in hirsutism and acne, controlled clinical trials on androgenetic alopecia (AGA, See Androgenetic Alopecia) have yet to be performed. Again, the woman of childbearing age should be admonished as to the potential risk to a developing male fetus and accordingly placed on contraceptive medication during use of cyproterone. Other side effects that have been manifested include menstrual irregularities, weight gain, breast tenderness, depression, nausea, and diminution of libido. Currently, cyproterone is not approved for use in the United States.
A method of correcting a bad previous hair transplant by placing multiple rows of good grafts (right size, angle, graft fit, gentle insertion, etc.) in front and around the bad previous grafts to de-emphasize their appearance while keeping them to enhance overall visual density.
The term used to describe how thick and full the scalp hair appears and the inability to see the underlying bald scalp (See also Camouflage).
An invagination of dermal tissue that is situated at the very bottom of the hair shaft in the bulbar region (See Bulbar Area) that contains collagen bundles, stroma, nerve fibers and a single capillary loop. The dermal papilla has powerful inductive qualities on the overlying matrix keratinocytes (See Matrix) to influence hair shaft growth. It is continuous with the perifollicular or dermal sheath of connective tissue in the lower hair shaft.
A product that is used as paint on the scalp to decrease the visibility of the scalp and thereby enhance the perceived density and camouflage (See Camouflage). Another type of camouflaging product is Toppik (See Toppik).
Diffuse Patterned Alopecia (DPA)
The term used to describe diffused hair loss that involves thinning but not true balding resembling the Norwood pattern. The occipital donor area is spared.
Diffuse Unpatterned Alopecia (DUPA)
The term used to describe general thinning across the entire scalp, albeit possibly more severe in the frontal and vertex areas. With involvement of the occipital region, hair transplant cannot be performed, as the transplanted hair will be lost.
For short, dihydrotestosterone is known as DHT. Conversion of testosterone to DHT can influence scalp hair loss in susceptible hairs in the fronto-temporal and vertex regions in androgenetic alopecia (See Androgenetic Alopecia). Finasteride (See Finasteride) blocks the conversion of testosterone to DHT through the enzyme 5-alpha reductase (See 5-Alpha-Reductase Inhibitor) and thereby can effect hair growth and reversal of minaturization (See Miniaturization).
A type of scalp condition that only leads to full-blown systemic lupus in about 10% of cases. Discoid lupus can lead to a cicatricial (or scarring) alopecia (See Cicatricial Alopecia) and accounts for about 30 to 40% of cicatricial alopecias. Another 30 to 40% arise from Lichen Planopilaris (See Lichen Planopilaris). The patchy areas of loss start out inflammatory in nature with red colored plaques that are heaped up and show centralized follicular hyperkeratosis (as opposed to peripheral in lichen planopilaris). The condition evolves into atrophic, white plaques over time. Unlike alopecia areata (See Alopecia Areata), the condition is inflammatory in nature and there is an absence of follicular ostia. Treatments include intralesional steroid, systemic steroid, and hydroxychloroquine. Hair transplant is not an option until the condition has burned itself out for a minimum of two years.
The donor area, also known as the safe donor area, is the region in the back of the scalp (occipital scalp) that remains throughout one’s lifetime even in the setting of advanced male pattern baldness or androgenetic alopecia (See Androgenetic Alopecia). This horseshoe shaped area is harvested during a hair transplant by strip harvesting (See Harvesting) and transplanted into the recipient area (See Recipient Area). What was discovered in the 1950s was that this occipital hair genetically programmed would not be lost when moved into bald areas of the scalp through a condition known as donor dominance (See Donor Dominance).
The number of hair in the donor area (See Donor Area) measured per square centimeter. The higher number of hairs per square centimeter, i.e., the greater the donor density, the more “paint”, i.e., hairs, that can be used to paint the “canvas”i.e., the bald scalp. An individual with high donor density can have a much higher chance of filling a wide area of baldness than someone with medium or low hair density. Donor density ranges in general between 80 to 120 follicular units per square centimeter.
The phenomenon discovered by the famed New York dermatologist, Norman Orentriech, in the 1950s that when hair was transplanted from the back of the head into the balding frontal region would continue to grow and not be lost, i.e., the transplanted hair would maintain the characteristic of the donor site and not be influenced by the recipient site. This is the principle of modern hair restoration but is not entirely true as the recipient site can have some influence (See Recipient Dominance).
Like finasteride, dutasteride is a potent inhibitor of 5 alpha-reductase; but, unlike finasteride, it targets both Type I and II enzymes. This dual action has been proposed as one mechanism by which dutasteride may be more efficacious in treatment of androgenetic alopecia (AGA, See Androgenetic Alopecia) – but this has not been clinically established. Although Type II 5 alpha-reductase is the principal enzyme localized to the scalp, Type I 5 alpha-reductase may still have an effect on the development of AGA. It is currently marketed as Avodart and is not FDA approved for AGA.
The quick glance one takes from another’s eyes up to his hairline back down to his eyes because there is something unnatural about the hairline but the observer does not want the other person to know that he or she is inspecting his artificial hairline.
The final part of the telogen phase of the hair cycle in which the hair shaft has been shed (See Telogen). Exogen hairs are invisible and therefore very skinny grafts that are made can risk loss of these invisible hairs.
Female Pattern Baldness
Hair loss that affects women of all ages but may be more prevalent in the post-menopausal setting. Hormonal influences like low thyroid, low iron level, or high testosterone can lead to female pattern hair loss. There are three principal types of female pattern hair loss: 1) Christmas tree pattern (See Christmas Tree Pattern), 2) diffuse central loss (See Ludwig Scale), and 3) male pattern baldness (See Androgenetic Alopecia). Also, women can suffer from chronic telogen effluvium (See Chronic Telogen Effluvium).
Finasteride is a prescription medication used in 5 mg dose to treat benign prostatic hypertrophy (enlarged prostate) and in 1 mg dose to treat androgenetic alopecia (See Androgenetic Alopecia). It was first discovered when treating patients with enlarged prostate with the 5 mg dose (marketed as Proscar) that men were regrowing their hair with stabilization of their hair loss. The 1 mg dose (Propecia) was found to be the appropriate dosage for balding men. It is taken as a once a day pill and can help regrow some lost hair and stabilize further hair loss (but not entirely). It takes about 6 months to a year to see the full effect, and the medication must be continued in order to maintain aesthetic results. Side effects include in less than 2% of men decreased libido, gynecomastia (breast enlargement), and breast tenderness. These symptoms are reversible upon stopping the medication and disappear in 58% of men who continue taking it. Women who are of childbearing age should not handle any crushed tablets, as they can have a birth defect in their male fetus’s sex organs (hypospadia). Men who take it will not have birth defects. Also men taking the medication must know that the prostate specific antigen (PSA), a marker for prostate cancer, can be decreased in half in those taking finasteride. Therefore, a baseline PSA should be measured before starting the medication in older men. Finasteride has been shown to benefit both the crown and other parts of the scalp as well. The mechanism by which finasteride works is through blocking the conversion of testosterone to dihydrotestoterone (DHT) via the enzyme 5-alpha reductase Type II, an enzyme found principally in the scalp and the prostate. DHT can influence hair loss in androgenetic alopecia. Although not FDA approved for post-menopausal women, some studies have shown benefit (and others have not) in post-menopausal women who take finasteride for hair loss. Finasteride works synergistically with minoxidil in the treatment of androgenetic alopecia (See Minoxidil).
5-Alpha Reductase Inhibitor
5-alpha reductase converts testosterone to dihydrotestosterone (DHT). 5-alpha reductase inhibitor like finasteride blocks the conversion of testosterone to DHT in the treatment of androgenetic alopecia (AGA, See Androgenetic Alopecia), or male pattern hair loss, as DHT can influence hair loss. Finasteride is a selective type II blocker, as 5-alpha reductase type II is found in hair follicles and the prostate (See Finasteride); whereas dutasteride blocks both type I (which is found throughout the body) and type II but is not FDA approved for treatment of AGA (See Dutasteride).
The name given to the hair shaft and related structures like the sebaceous gland that grow from the scalp. Follicles tend to grow in clusters known as a follicular unit (See Follicular Unit). From inside out, the layers of the hair follicle are as follows: hair shaft (medulla, cortex, cuticle), inner root sheath (inner root sheath cuticle, huxley’s layer, henle’s layer), outer root sheath, glassy membrane, and connective tissue sheath.
Follicular Degeneration Syndrome
A type of non-inflammatory cicatricial alopecia (See Cicatricial Alopecia) that principally affects the vertex in African-American women. Initially thought to be caused by the drip of hot wax during hair treatments, hence the former term hot comb alopecia, Sperling found that this type of scarring alopecia occurs in African-American women who do not or rarely use hot wax or hot combs. Therefore, it is recognized as a distinct pathology that may be related to pseudopelade of Brocq (See Pseudopelade of Brocq). With folliculitis decalvans and pseudopelade of Brocq, follicular degeneration syndrome represents one of the central centrifugal cicatricial alopecias (See Central Centrifugal Cicatricial Alopecia).
The description for two follicular units (See Follicular Unit) that reside very close together in a highly dense donor area (See Donor Area) that can be considered for all intents and purposes as a single follicular unit graft (FUG, See Follicular Unit Graft) even though technically it is a multiple-unit graft (See Multiple-Unit Graft).
Placing two follicular unit grafts (FUG, See Follicular Unit Graft) into one recipient site to create a larger single graft in an area like the central scalp that would benefit from larger sized grafts when there is an insufficient number of these larger sized follicular units.
First described by Headington in the 1980s, the follicular unit describes how hairs grow in the scalp in discrete clusters of 1 to 4 hairs and not singly. Technically, the number of hairs growing in a follicular unit is defined at the mid-dermal level. The follicular unit is the basis for modern hair restoration, as hair grafts are divided along these natural cleavage planes, creating follicular unit grafts (FUG, See Follicular Unit Graft). At times, combination grafting technique (See Combination Grafting) is used in the right candidate to increase visual density in a single session without sacrificing naturalness by enlisting multi-unit or multiple-unit grafts behind and central to the FUGs (See Multiple Follicular Unit Graft)
Follicular Unit Graft (FUG)
A follicular unit graft (FUG) is a hair graft that comprises a single follicular unit (See Follicular Unit and Follicular Unit Transplant).
Follicular Unit Extraction (FUE, also FOX, also FIT)
A type of hair transplant technique that involves removing a single follicular unit (See Follicular Unit) at a time from the back of the scalp or from the body rather than via conventional strip harvesting. The benefit of this procedure is the absence of an incision line in the donor area, a concern that is much less problematic with current methods of closure (See Trichophytic Closure). FUE is costly and can run 4 times the cost of conventional strip harvesting and grafting with a quarter of the number of transplanted hairs. Also, growth rates are less than stellar compared with conventional strip techniques even in experienced hands. FUE can be used in select cases for optimal advantage: 1) in a patient with a tight donor scalp that has already undergone multiple previous transplants and can no longer have a strip harvested, 2) removal of body hair for scalp transplantation can only be done through this method, 3) punch grafting out plugs and recycling them for use elsewhere, and 4) to graft hair into an unsightly donor area scar.
Follicular Unit Transplant
Also known as a total follicular unit transplant or TFUT. This technique of hair transplant involves transplanting only individually divided follicular units (See Follicular Unit) via follicular unit grafts (FUG, See Follicular Unit Graft) rather than ever separating follicular units (See Micro-Grafting) or combining them (See Combination Grafting and Multiple-Unit Grafting). In patients with very coarse, dark hairs or in those individuals with very tight arrangement of existing hairs, TFUT is ideal. However, growth rates can be compromised and overall density less than ideal when compared with combination grafting methods. The Lam Institute for Hair Restoration uses both TFUT and combination grafting depending on the patient’s degree of hair loss and quality and type of donor hair.
A type of inflammatory cicatricial or scarring alopecia (See Cicatricial Alopecia) that arises from one’s response to the natural skin flora (i.e., bacteria) on the scalp leading to pustules, chronic infection, and scarring. Treatment involves anti-staphylococcal antibiotics possibly with rifampin to combat the infection and related scarring and possibly in more extreme forms removal of the hair through laser hair removal to minimize the origin of scarring which is the hair shaft. Folliculitis decalvans (FD) can be distinguished from the two more common types of cicatricial alopecia (discoid lupus and lichen planopilaris) in that FD has a pustular quality versus a lymphocytic infiltrate in the other two types. FD also has a predilection for the vertex and therefore is known as one of the central centrifugal cicatricial alopecias (See Central Centrifugal Cicatricial Alopecia).
See Central Forelock
Frontal Fibrosing Alopecia
A rare condition that affects mostly postmenopausal women over the age of 50 years (mean age is 67 years) in which hair loss is distributed over the frontal and temporal regions and may involve the eyebrows. A scalp biopsy will show scarring alopecia with lichenoid changes. Although some experts have argued that this condition is a variant of lichen planopilaris, this contention is disputed. The disease is usually progressive in nature but may stabilize after a few years. There is no real treatment for the condition but oral steroids or antimalarials can benefit patients. Albeit less commonly, this condition can also be found in men.
One of the hallmarks of male pattern baldness or androgenetic alopecia (See Androgenetic Alopecia) in which the hair is lost along the lateral edge of the hairline and the anterior temporal hair in an unzipping pattern. This fronto-temporal hair loss can be the earliest signs of hair loss in a Norwood II or III type (See Norwood Classification). Fronto-temporal recession characterizes hair loss in Asians and Caucasians but is less commonly found in African-Americans who oftentimes maintain a more right angle in the fronto-temporal region and lose the hairline progressively in a uniform fashion.
The formal name is the galea aponeurotica which describes the layer of the scalp (See Scalp) that lies in between the subcutaneous tissue (above it) and the loose connective tissue (below it). The galea represents the tendinous attachment between the frontalis muscle in the forehead that elevates the forehead and the occipitalis muscle in the back of the head. The scalp is relatively immobile except for its ability to glide, which is made possible due to the galea sliding over the loose aponeurotic space below. This fact permits reduction in wound tension during closure if the donor hair area is closed only in the subcutaneous plane. That is why the subgaleal (below the galea) plane should be respected during donor harvesting (See Harvesting). However, when performing an alopecia reduction (See Alopecia Reduction) or tissue expander (See Tissue Expansion), the plane of dissection is below the galea so that the galea can be stretched out. Without stretching the galea, the wound will not close when taking out significant amounts of tissue or when trying to expand the tissue for tissue flap.
The term used to describe the dissected tissue that contains various numbers of follicles and used to transplant into the bald regions of the scalp (or other parts of the face and body). The two major types of grafts are the follicular unit graft (FUG, See Follicular Unit Graft) and the Multiple-Unit or Multiple Follicular Unit Graft (See Multiple-Unit Graft). The terms micro-grafting and mini-grafting (See Micro-Grafting and Mini-Grafting) are less precise terms that are not as favored in current parlance to describe the types of hair grafts used in hair transplant surgery.
Hair Feathering Test
Grasping the end of the hairs and pulling forcefully can reveal easy breakage of the hair shafts. If multiple fragments appear in one’s hands, this result can indicate excessive weathering of the hair or some abnormal hair shaft breakage.
A bit of a misnomer since the created “hairline” is not truly a line but a zone of transition from single hairs per graft to 2 hair grafts behind the first 2 to 3 cm. The hairline appears like an irregularly irregular line like a coastline appearance with occasional single hairs that stand in front of it known as sentinel hairs.
A measurement of hair density that incorporates both the number of hairs per square centimeter (See Donor Density) and the hair shaft diameter – that is a better reflection of how dense a hair transplant result will look like. After shaving a 4 cm2 (2 x 2 cm) box in the donor region, the hair in that box is bundled and twisted. A knot of string is tied around the twisted column of hair and a marker used to mark where the string touches itself. This marked distance represents the circumference. The cross sectional area is then calculated and divided by 4 to determine the hair-mass index.
See Hair System
The hair shaft is composed from inside to outside: the medulla, the cortex, and the cuticle. The inner root sheath surrounds the hair shaft, and the outer root sheath surrounds the inner root sheath.
A hair system is also known more colloquially as a hairpiece, a toupee, and a wig – although a wig technically is a more all encompassing hair system in which there is no exposure of any of one’s natural hairs at all and usually refers to types used by women. The hair system is the preferred way of discussing a hairpiece, as the terms hairpiece and toupee have a pejorative and negative connotation in our society. Hair systems have truly evolved today to look much more natural than they ever did in the past with woven systems, for example, that look like hairs emanating out of the scalp rather than hairs simply sitting on top of the scalp. Despite the advent of much more natural appearing hair systems, the four major reasons that have limited their widespread acceptance are as follows: a high level of daily, weekly, and monthly maintenance; the related costs of this maintenance; the inability to engage in certain social activities (like swimming or being careful near flammable objects); and the social stigma of having a hair system. Nevertheless, for an individual desiring a full head of hair that has a Norwood VII (see Norwood Classification) or a lesser degree of a Norwood staging but poor donor density, a hair system can be the only option available.
Hair Transplant Technician
An individual specially trained to dissect hair grafts and to assist the surgeon during a hair transplant surgery.
See Norwood Classification
The term used to describe removing hair from the donor area (See Donor Area) along the back of the head (occiput) and extending toward the temporal region during hair transplant. The harvested strips will then be cut into slivers (See Slivering) and in turn into individual grafts which can be used to transplant into the bald recipient area.
Inner Root Sheath
The inner root sheath extends from the bulb up to the bulge area and disappears altogether in the region of the isthmus. There are three layers of the inner root sheath: from outside to inside they are Henle’s layer, Huxley’s layer, and the inner root sheath cuticle. The inner root sheath is responsible for anchoring and directing the growth of the emerging hair shaft.
The infundibulum describes the portion of the hair shaft that extends from the sebaceous gland up toward the opening of the skin. It is lined by epithelium and can be the source for skin regeneration in cases in which the skin is partially lost like in laser skin resurfacing. The infundibulum and the isthmus immediately below it (See Isthmus) constitute the upper portion of the hair shaft which is considered the permanent part of the hair shaft that does not change during the hair cycle.
The isthmus is the region of the hair shaft immediately below the infundibulum (See Infundibulum) that extends from the bulge area (See Bulge Area and Arrector Pili Muscle) to the sebaceous gland opening. Along with the infundibulum, the isthmus constitutes the permanent part of the hair shaft. The outer root sheath in the isthmus exhibits a different type of keratinization called trichilemmal as opposed to the epithelial like keratinization in the infundibulum. Therefore, certain types of cysts can arise in this area, e.g., trichilemmal cysts, pilar cysts, and isthmus cysts.
A flap that is also more formally known a temporo-parieto-occipital flap used to reconstruct the hairline and midscalp by Jose Juri from Argentina. The Juri flap is twice delayed in that the flap is cut along the proposed edges without elevating or transposing it followed a week later by raising the entire flap and resetting it back down to its original position followed a week later by lifting and repositioning/rotating the entire flap to rebuild the hairline and midscalp. The reason for the twice delay is to increase the blood supply to the flap by separating it from its surrounding tissue before actually raising and rotating the flap. A second flap can be harvested from the other side in the same fashion and placed behind the first flap. The flap has fallen out of favor today for several reasons: 1) the advances of follicular unit grafting have made it less necessary, 2) the procedure has higher risk in that flap loss could lead to significant loss of usable donor hair, 3) the high density of hair in the hairline can appear unnatural without further hair grafting to refine the look, 4) the straight appearance of the hairline can also appear artificial without further grafting, 5) the hairs that are rotated grow in the opposite direction of how hairs in a natural hairline grow, i.e., they face backward when they should face forward, 6) unnatural patterns can develop behind the flap making the flap appear as a solitary island or islands of hair, and 7) greater technical skill is necessary to perform the procedure.
The short fine hair that develops in utero on the fetus that tend to disappear by the 32nd to 36th week of gestation. These follicles start to grow from the head and extend downward across the remainder of the body. They remain in up to 1/3 of newborn babies and are replaced shortly by vellus hairs and later terminal hairs (See Vellus Hairs and Terminal Hairs).
The term used to describe the lateral most portion of the midscalp (on both sides of the head) before transitioning more laterally to the lateral hump hair (See Lateral Hump). The hairs are directed primarily forward and begin to slope away when they approach the lateral hump. It is a term used by hair transplant surgeons to describe a specific region of the midscalp.
The lateral hump describes the rounded portion of the temporal hair that frames the head laterally. In ongoing recession, the lateral hump appears like an upside down U shape that recedes gradually downward toward the ear. The superior edge of the lateral hump meets the lateral crease of the midscalp. The juncture of the lateral hump and the lateral crease falls along a line drawn vertically through the outer (or lateral) canthus of the eye. The angles of hairs that grow in this region (that must be recreated during hair restoration) follow a forward direction that gradually slopes and falls downward.
This type of cicatricial or scarring alopecia (See Cicatricial Alopecia) accounts for 30 to 40% of scarring alopecias. The characteristic appearance of this inflammatory type of cicatricial alopecia is follicular hyperkeratosis that occurs in the periphery of active scalp lesions (as opposed to central hyperkeratosis seen in discoid lupus, See Discoid Lupus). It is treated with intralesional steroid, systemic steroid, and possibly hydroxycholoroquine. Hair transplant is not an option until the disease is burned out.
The scale for describing a type of female pattern hair loss (See 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. Ludwig III’s require a minimum of a metabolic workup and possible scalp biopsy to determine any reversible causes of the hair loss.
Male Pattern Baldness
See Androgenetic Alopecia.
The matrix keratinocytes that originate in the bulbar region (See Bulbar Area) of the hair shaft are responsible for the active mitotic growth of the hair shaft during anagen (See Anagen) and are influenced and directed by the adjacent dermal papilla.
An outdated term that was first introduced in the 1980s to describe 1 or 2 hair grafts irrespective if those grafts are derived from a follicular unit or not (See Follicular Unit Graft).
A term used to describe the area behind the hairline that extends laterally toward the lateral hump (See Lateral Hump) and posteriorly toward the vertex transition point (See Vertex Transition Point). The central forelock (See Central Forelock) occupies the anterior central portion of the midscalp. It is an area ideally suited for multiple follicular unit grafts in the right candidate to increase visual density following hair transplant (See Multiple-Unit Graft and Combination Grafting).
The process in which terminal hairs are transformed into vellus hairs and vellus-like hairs in male pattern baldness or androgenetic alopecia (See Terminal Hairs, Vellus Hairs, Vellus-Like Hairs, Androgenetic Alopecia). The change from long, thicker terminal hairs to wispy, short, and thin vellus hairs creates a marked decreased in visual density of one’s hair.
An outdated term used to describe larger grafts than a micro-graft (See Micro-Grafting) but without necessary respect for a follicular unit. The micro-graft can be either a larger follicular unit graft (See Follicular Unit Graft), a multiple follicular-unit graft (See Multiple-Unit Graft), or what was once called a quarter graft, which was a quarter slice of the old 4-mm round plugs (See Plugs).
The trade name for minoxidil is Rogaine in the United States. Minoxidil is an over-the-counter topical medication applied directly to the scalp (not hair) twice daily to help slow down and reverse the process of hair loss in men and women. It comes packaged in a 2% and 5% concentration for women and men, respectively. Women can use the 5% concentration if they do not get unwanted hair growth on their face for faster results in hair growth that over a year will become the same as using the 2%. Minoxidil is now off patent and can be bought as a generic form with the same efficacy as the brand name. However, the brand name Rogaine has released a 5% foam product that affords two advantages: 1) removal of propylene glycol that reduces the incidence of dermatitis significantly and 2) is easier to style one’s hair after application. It is unclear exactly how minoxidil works on regrowing scalp hair, as it works on the potassium channel as an agonist. There can be some temporary shedding of hair after just starting minoxidil through a process of immediate telogen release, i.e., the hair synchronously is released from telogen phase into anagen. Minoxidil can help regrow hair throughout the scalp with particular efficacy in the crown region. It usually takes 4 to 6 months to see the benefit and the product must be continued indefinitely to maintain the results. In men, it can be taken with finasteride (See Finasteride) in order to enhance overall effect.
Multi-Unit Graft (MUG)
See Multiple-Unit Graft
Multiple-Unit Graft (MUG), or Multiple Follicular-Unit Graft
A graft that comprises 2 to 3 follicular units used to increase visual density in the central midscalp and combined with single follicular unit grafts (See Follicular Unit Graft) in the hairline, temple, and vertex (See Combination Grafting).
The Norwood classification for male pattern baldness was first proposed in 1975 by O’Tar Norwood. 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 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.
Outer Root Sheath
The outer root sheath is part of the hair follicle that extends from the bulb up to the sebaceous gland at which point it is transformed into the skin epidermis. It circumscribes the inner root sheath and changes from a thin layer to an increased thickness as it approaches the surface of the skin, undergoing trichilemmal keratinization in the isthmus. The progenitor cells are thought to originate from the bulge area rather than from the matrix.
The divoted look of grafts in which the skin surface of the graft appears lower than the surrounding skin. This condition is hard to correct but can be improved by de-emphasis grafting (See De-Emphasis Grafting) and/or selective punch removal. This condition arises due to poor placement in which the graft is placed too deeply during graft insertion. Or, the graft size is too small relative to the recipient site so that the graft slides too low relative to the recipient site. The opposite problem is cobblestoning (See Cobblestoning).
A colloquial expression that describes the old 4-mm round punches that dominated early hair transplant efforts prior to the 1990s that rendered a cornrow or unnatural look due to their large size. An unnatural result of this kind has been referred to as “pluggy”.
With cicatricial alopecia (see Cicatricial Alopecia), the scarring that occurs obliterates follicular ostia and causes remaining ostia to coalesce so that several follicles emerge out of one site. This is also known as tufting.
Posterior Parietal Pocket
The triangular area that may be targeted for hair restoration that resides just above the crown (above the vertex transition point) laterally.
See Vertex Transition Point
Pseudopelade of Brocq
In 1885, Brocq of Paris identified what he called Pseudopelade. Pelade is the French word for alopecia areata (AA, See Alopecia Areata), which has led to some confusion about this entity because it is not AA. AA does not lead to scarring and follicular ostia are therefore preserved. Pseudopelade is a scarring type of alopecia (See Cicatricial Alopecia). However, unlike discoid lupus and lichen planopilaris (DL, LPP, See Discoid Lupus and Lichen Planopilaris), pseudopelade is non-inflammatry. In fact, some believe that pseudopelade represents burned out CCLE or LPP. However, Braun-Falco has shown that pseudopelade can represent a distinct entity. The classic appearance of pseudopelade is the so-called “footprints in the snow” that appear in the parietal and vertex regions of the scalp. Occasionally, pseudopelade can also affect other non-scalp regions like the beard. Follicular Degeneration Syndrome (FDS, See Follicular Degeneration Syndrome) overlaps with pseudopelade as another example of non-inflammatory cicatricial alopecia.
Approximately 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. The patient must not shampoo for at least one day prior to the pull test.
Punch grafting refers to removal of hair grafts using a round punch of various sizes. Traditionally, hair transplant was performed in the 1950s to even 1980s with punch grafting, using the old 4 mm round punch leading to a pluggy appearance (See Plugs). Today, punch grafting is used for two reasons: 1) to remove partially or totally old plugs, which can be recycled elsewhere as smaller grafts and 2) as an alternative method of harvesting different from strip harvesting (See Harvesting) in a process known as follicular unit extraction (FUE, See Follicular Unit Extraction). The size of the current FUE punch is approximately 1 to 2 mm (or smaller) in size compared with the 4 mm round punch of the past.
This interesting phenomenon stands in distinction to donor dominance (See Donor Dominance) but can co-exist with donor dominance. Recipient dominance refers to the influence of the recipient site scalp on the growth of transplanted hairs. For example, hair that is transplanted from the back of the scalp to the eyebrows can start to slow down after a year or two (but not always) so that growth rate more closely matches the native eyebrow region by virtue of influencing factors of the recipient eyebrow region.
The tiny slits created during hair transplant by the hair-transplant surgeon that will accommodate the hair grafts. The slits are made with various instruments depending on the size of the intended graft for that slit with smaller ones made toward the front and larger ones toward the center of the scalp. The angle, direction, and pattern of the recipient sites are dictated by the artistry and technical precision of the surgeon that will influence the ultimate result in terms of naturalness and perceived density.
Saw Palmetto (Serenoa Repens)
The extract taken from the red saw palmetto berries of the small plant called Serenoa Repens is thought to inhibit 5-alpha reductase and the binding of DHT to androgen receptors. A few double-blinded, placebo-controlled studies conducted in Europe have determined the efficacy in treatment of BPH. However, the role for Saw Palmetto in androgenetic alopecia (AGA) is unclear at best. Some recent evidence has shown that it is not very effective in treating AGA.
There are five layers to the scalp that can be remembered by the mnemonic S-C-A-L-P. S stands for skin. C is subCutaneous tissue that is composed principally of fat. A is for aponeurotica galea (See Galea). L is the loose subgaleal connective tissue that accounts for how the scalp can glide over the skull. The P is the pericranium or periosteum that lines the skull.
A device made of silastic (silicone) sheeting that can stretch out and with titanium hooks on both sides used during Scalp Extension. See Scalp Extension.
A process for alopecia reduction (AR, See Alopecia Reduction) first developed by famed surgeon Patrick Frechet of France in order to minimize unfavorable stretchback (See Stretchback) of reduced bald scalp following AR, to encourage positive shrinkback (See Shrinkback) in which the reduced bald area is actually further reduced following AR, and to reduce the interval and number of ARs needed. A scalp extender is a silastic sheet that can stretch at least 2 to 1 the length of its unstretched state with titanium hooks that are placed under the opposing sides of the galea (See Galea), i.e., on both sides of the cut wound edge. The silastic sheet shrinks back over time stretching the hair-bearing scalp (which is good) and shrinking the bald region between the tines of the extender as the extender returns to its original size. Generally only 2 ARs are needed with an interval of about a month in most cases compared with an interval of 2 to 3 months and further ARs that are necessary without a scalp extender in place. Scalp extension is like tissue expansion but without the intervening deformity since the scalp is relaxed in a flat plane (See Tissue Expansion).
Older terminology for Alopecia Reduction. See Alopecia Reduction.
See Cicatricial Alopecia
Also known as senescent alopecia. A condition in individuals over 50 years of age who begin to have noticeable hair thinning even though they never had it up until middle age. In post-menopausal women, there can be a component of androgenetic alopecia (AGA). Unlike in AGA, there is a relatively normal number of telogen hairs and no abnormal miniaturization.
Sentinel hairs refer to the single-hair follicular unit grafts (See Follicular Unit Graft) that reside in front of the hairline to soften the appearance of the hairline and also to replicate what exists in normal non-balding hairlines.
The placement of acute angled (30 degrees or so) hair grafts that are layered in a staggered appearance like the tiles on a roof in order to increase the shadow on the scalp like a shingle or awning and thereby decrease scalp show and increase perceived hair density. The degree of shingling is principally dictated by the skill of the hair-transplant surgeon when making recipient sites (See Recipient Sites).
The phenomenon during an alopecia reduction (AR, See Alopecia Reduction) when using a scalp extender (See Scalp Extender and Scalp Extenstion) in which the central bald scalp that is reduced is further reduced by the return of the scalp extender back to its original non-stretched size.
Slivers and Slivering
Slivering is a process that the hair-transplant technician (See Hair-Transplant Technician) performs after the donor strip is harvested in preparation for dissecting the tissue into individual grafts. The donor strip is cut transversely into a single row of follicular units that are referred to as slivers (and the process slivering) so that this single row sheet of follicular units can then be cut and trimmed into individual hair grafts.
Like cyproterone acetate, spironolactone acts as an androgen receptor blocker; and, therefore, these types of medications that bear systemic anti-androgen effects are contraindicated in men. Oral spironolactone, an aldosterone antagonist, competitively inhibits the androgenic receptor and weakly interferes with adrenal androgen biosynthesis. A few clinical trials have supported the use of spironolactone in AGA, but further work is necessary to confirm these initial findings. Oral spironolactone has demonstrated a greater role in the treatment of hirsutism than in AGA. Topical spironolactone has also been evaluated for use in male patients with AGA but is now only in a preliminary phase of investigation. Side effects of spironolactone principally concern menstrual difficulties but may also give rise to precipitous increase in blood potassium.
The phenomenon during an alopecia reduction (AR, See Alopecia Reduction) in which both hair-bearing scalp and non hair-bearing scalp stretchback so that in essence you take 2 steps forward and 1 step back. With the introduction of the Frechet scalp extender (See Scalp Extender and Scalp Extenstion), the stretchback would occur only in hair-bearing tissue (favorable stretchback) and would be avoided in the non hair-bearing scalp (unfavorable stretchback). In addition, the extender would promote shrinkback (See Shrinkback) in which the non hair-bearing scalp would not only NOT stretchback but would even get smaller or shrinkback as well.
The third phase of the hair cycle following anagen and catagen phases. The telogen phase occurs in approximately 10% of non-balding scalps and can be proportionately higher in androgenetic alopecia (AGA, See Androgenetic Alopecia). The telogen phase lasts generally about 2 to 3 months and is characterized by the preparation for expulsion of the hair. Stenn has proposed a name for the phase in which the hair is shed, as exogen (See Exogen), which is a controlled and timed event.
Telogen effluvium relates to hair shedding that occurs when hairs enter the telogen phase more readily. Certain inciting events that can cause telogen effluvium are fever (8 to 10 weeks following fever), postpartum, crash dieting/low protein, low thyroid levels, iron deficiency, prolonged anesthesia, malignant disease, renal failure, liver disease, acute anxiety, and depression. There is also a distinct entity known as chronic telogen effluvium (See Chronic Telogen Effluvium). There are
5 types of telogen effluvium
Immediate Anagen Release:
Hairs that would otherwise stay in anagen are released into telogen prematurely. It is thought that some drugs can cause immediate anagen release.
Delayed Anagen Release:
Certain conditions can extend the anagen phase which can then go into telogen in a more synchronous phase like in the postpartum setting when hairs sustained in anagen are released into telogen with loss of the influence of estrogen.
This occurs when the anagen phase is shortened. If the anagen phase is halved, telogen is concomitantly doubled. Etritinate is thought to cause a shortened anagen.
Immediate Telogen Release:
Follicles that are normally in telogen for 4 to 12 weeks are cycled more quickly into anagen in a matter of days. This is thought to occur with minoxidil, as some individuals have increased hair shedding early on.
Delayed Telogen Release:
With delay in telogen, there can be a slightly more synchronous growth leading to perceived hair loss.
The hairs that lie lateral (outside) of the lateral canthus (outer part of the eye). Temporal hair should fall down and outward rather than be combed over the hairline (See Combover). The upside down U-shape that is centered over the ear is the part of the temporal hair known more precisely as the lateral hump (See Lateral Hump).
See Juri Flap
The most anterior border of the temple can jut forward into an almost right angled configuration of hair known as the temporal point. Temporal points can be classified into the following: N = no thinning or recession of the temporal point, T = thinning and mild recession, P = recession is parallel to the anterior sideburn line, R = recession has caused a reversed angle that is usually anteriorly convex but now is concave. The N, T, P, R designation can be appended to the Norwood Classificaiton (See Norwood Classification). Generally only P, R’s would benefit from transplantation. The best match of color and caliber is found in the supra-auricular region. A good rule of thumb when designing the temporal point is to look at the point where two lines intersect: a line drawn from the earlobe through the central anterior hairline (trichion) and a line drawn from the tip of the nose through the mid-pupil of the eye.
Terminal hairs are the thick hair on the scalp that is found in the non-balding scalp and which are slowly converted to vellus and vellus-like hairs (See Vellus and Vellus-Like Hairs) in androgenetic alopecia (See Androgenetic Alopecia). Terminal hairs are more than 60 microns in diameter and can grow to over 100 cm in length. The hair bulb is located in the subcutaneous plane.
A process for correcting alopecia usually of a traumatic nature but can be for other types of alopecia as well. Tissue expansion requires surgical placement of a silastic tissue expander in the subgaleal plane (See Galea) and then gradually expanded over time to stretch the hair-bearing region in order to create new tissue. The tissue expander is first filled just to the point to close off any dead space. Then 2 weeks later, the expander is expanded with 40 to 60 cc of sterile fluid under sterile conditions until the patient begins to feel some discomfort, which usually subsides after several hours. The scalp will soften in 2 to 3 days allowing for another inflation in 3 to 7 days. Generally, most scalp expansions can be completed in 10 to 12 weeks. When the scalp has reached its fully expanded state, the tissue expander is removed and the extra tissue is then used as a flap to cover the area of alopecia. The tissue expander works through a process of stretch, creep, dehydration, and stress relaxation. Stretch occurs when the skin is placed under tension so that the collagen fibers become aligned. This process is reversible. Next, creep comes into play, which describes the irreversible stretching of the skin beyond this point which in turn is partly afforded by relative dehydration of the skin and the stress relaxation that occurs. Stress relaxation refers to the ongoing diminution of required force to maintain a stretched skin with continued traction.
Powder made of pure organic keratin protein and manufactured by Spencer Forrest used to temporarily camouflage balding by spraying or dusting it on the hair. The particles are magnetically drawn to the hair follicles and are used to create the illusion of denser hair. DermMatch is another type of camouflaging agent (See DermMatch).
See Hair System
A type of irreversible hair loss that arises due to traction or pull on one’s hair for an extended period of time most commonly arising from tight hair braiding in the African-American community.
Also known as congenital triangular alopecia and temporal triangular alopecia. This condition may be present at birth or acquired during the first decade of life. Lesions can be acquired during adulthood or in other regions of the scalp, but this is rare. The hair loss is in a lancet distribution and can be unilateral or bilateral with the lancet edge pointing superiorly and posteriorly. The area may be entirely hairless or have small vellus hairs scattered throughout. There is normal skin structure and no signs of inflammation. In addition, there are no fibrous stelae like in androgenetic alopecia, as minaturization most likely occurred in utero without terminal hairs ever forming.
The central anterior part of the hairline.
The trichogram or pluck test involves capturing 60 to 80 hairs in a hemostat covered with rubber, which is then plucked, twisted and rapidly lifted to remove the hair follicles. The hair shaft is then cut off 1 cm above the root sheath and arranged on a slide for evaluation of anagen to telogen ratio and related pathology. Today, the trichogram is considered outdated since a scalp biopsy provides better information. Also anagen hairs that are uprooted can appear dystrophic (abnormal) due to the force of the removal and not due to an underlying pathology.
A type of specialized closure of the donor scalp performed by removing 1 mm of the inferior skin edge, which permits overlap of the upper epidermis over the exposed lower edge so that hairs will grow through the scar and make it less detectable.
See Vertex Transition Point
Vellus hairs are less than 0.03 mm in diameter, do not possess a medulla and grow less than 2 cm in length. Vellus hairs have a thin outer root sheath and originate in the upper dermis. Vellus hairs are transformed into terminal hairs in the genital/axillary and trunk and beard for men under the influence of androgens at the onset of puberty.
Vellus-like hairs are distinguished from vellus hairs in that the former have a thick outer root sheath originating from the terminal hair. Vellus hairs have a thin outer root sheath and originate in the upper half of the dermis.
The circular area in the back of the head, which is also known as the crown. The vertex is primarily affected in androgenetic alopecia (See Androgenetic Alopecia) and can be stabilized and somewhat reversed with finasteride and/or minoxidil (See Finasteride and Minoxidil). Hair transplant must follow a natural whorl (See Whorl) pattern in the vertex and also plan ahead for possible further recession in this area. The vertex is an unsuitable area to fill for anyone in his twenties and possibly even early to mid 30s.
Vertex Transition Point
Also thought of as the posterior hairline, the vertex transition point is a crescent-shaped line that marks the end of the midscalp and the beginning of the crown. The line falls along the transition from the vertical scalp plane of the vertex to the horizontal plane of the midscalp. It is an important line in hair transplant surgery as the posterior limit when transplanting the hairline and midscalp.
Whorl, or Whorl Pattern
A whorl describes the circular spiral pattern that exists in the vertex and that must be meticulously recreated during hair transplant surgery.
The small jetty that juts out of the central hairline. It can visually break a hairline that is too rounded and it can also make the hairline appear lower in someone who desires a lower hairline but should not have a lower hairline for aesthetic reasons or to preserve grafts for elsewhere on the scalp.