Upper part of the bulb.
Divided into 6 layers:
3. Hair cuticle
4. Cuticle of inner sheath
5. Huxley’s layer
6. Henle’s layer
Varies according to the phase of hair cycle.
Composed - specialized fibroblast like cells
embedded in extracellular matrix.
Contains a loop of capillary blood vessels.
Volume of dermal papilla maybe responsible for
controlling size of hair follicle.
3 layers :
1. Maybe continuous, interrupted or absent.
2. Contains few layers of rounded cells containing
1. Forms bulk of the hair shaft.
2. Consists of numerous layers of flattened elongated
cells packed together.
1. Consists of 5 – 10 layers of flattened cells arranged in
overlapping “roof – tile” pattern.
2. The upwards pointing edges of the hair cuticle
interlock with the downwards pointing edges of
cuticle of inner sheath.
Inner Root Sheath
1. 3 layers :
2. At the Isthmus the IRS disintegrates
Outer Root Sheath
1. Most peripheral part of hair follicle.
2. Keratinize at the level of Isthmus.
3. Occasionally “companion layer” maybe seen in
between IRS and ORS.
Ultra structure of Hair
Hard keratin with high
High sulfur content -
extraordinary tensile strength.
S-H linkages of cysteine at
the bulb are converted to
S-S linkages of cysteine
Functions of Hair
Protection of scalp from sunlight and trauma.
Protection of eyes from foreign bodies, sunlight &
Screening nasal passages.
Reduce friction in intertriginous areas.
Disseminates apocrine odor
Contributes to psychological perception of beauty &
• Period of active hair growth.
• Duration of this phase resp. for
final length of the hair.
• Usually lasts for 2 – 6 years.
• Duration of Anagen genetically
• About 85% of all hairs are in
this phase at any time.
• Onset of mitotic activity of
epithelial cells in Dermal
Lower part of follicle elongates downwards along
a preformed dermal tract ( stele ).
Dermal papilla expands .
A network of capillary blood vessels develop
around the lengthening follicle.
Epithelial cells in the hair bulb undergo vigorous
The melanocytes become active adding colour
to this newly forming hair.
Anagen consists of 6 substages.
Differences in the length of hair is due to
variable duration of the last stage ( VI ).
• Short transition stage that
occurs at the end of the
• Signals the end of active
growth of hair.
• Usually lasts about 2 – 3 weeks.
• At the end of Anagen, epithelial
division declines and ceases.
• Proximal end of the hair shaft
keratinizes to form a club
Lower part of the follicle involutes by
Basement membrane surrounding the follicle
becomes thickened to form “glassy membrane”.
Base of the follicle along with dermal papilla
moves upwards to lie below the level of
Arrector muscle attachment.
• Resting phase of the hair
• Usually lasts for about 3
• About 10 – 15% of all hairs
are in this phase at any time.
• Quiscient period between
completion of follicular
regression and onset of next
• Resting club hair lies within
an epithelial sac.
Types of HAIR
Lanugo (wool like)
Fine, soft, unmedullated, unpigmented
Vellus Hair ( ≤0.03 mm )
Soft, unmedullated, pigmented
Terminal Hair ( ≥0.06 mm )
Coarse, medullated, pigmented
Modulators of Hair Follicle Cycling in Humans
Androgens Promote miniaturization of follicles & shorten
duration of the anagen stage in androgen
sensitive areas of scalp;
Enlarge follicles in androgen- dependent areas
Estrogens Prolong anagen stage;
Post partum reduction in estrogen- telogen
Growth hormone Acts synergistically with androgen in
Prolactin Can induce hirsutism
Thyroxine Low levels can cause telogen effluvim;
High levels may have similar effect 26
Anabolic Steroids Accelerate androgenetic alopecia :
Causes telogen effluvium
Estrogen Prolong duration of anagen stage
Finasteride Blocks 5 α Reductase type II
Minoxidil Induces and prolongs anagen stage & Vellus
OCP Cessation may cause telogen effluvium
Retinoids Premature onset of catagen stage
Rate of Hair Growth :
Part of the Body Rate of Growth
Forehead(vellus hair) 0.03mm/day
Role of Growth Factors & Cytokines in Hair Follicle
Development,Hair growth & Hair Cycle Activity
EGF 1. Delays follicular development
2. Retards hair growth & cycling
3. Induces follicle regression & catagen–like changes in vitro
4. Stimulates elongation of hair.
TGFα 1. Controls normal positional development of hair follicle
2. Retards hair growth in vitro in mice
1. Responsible for formation & maintenance of perifollicular
2. Important for skin appendage morphogenesis & their
FGF4 1. Necessary for follicular development & epithelial
FGF5 1. Hair elongation inhibitor
2. Initiates transition from anagen to catagen phase 29
VEGF 1. Responsible for maintenance of the
perifollicular capillaries in anagen
TGFβ -1,2,3 1. Inhibits follicular development
2. Gene over expression in epidermis marked
reduction of epidermal & follicular proliferation
& dec. number of follicles in mice
BMP-2, BMP-4 1. Necessary for epithelial regeneration
NBFβ 1. Probably trophic functions for neurons
2. Probably responsible for maintenance of
perifollicular nerves in anagen
TNFα 1. Responsible for induction of apoptosis
PDGF-A,B 1. Important in follicular development &
2. Stimulates hair canal development 30
Alopecia is defined as “ absence or loss of hair”.
It’s a chronic disorder secondary to the disease of
either the hair follicle, hair shaft or the scalp.
Pseudoalopecia is defined as acute or chronic breakage
of hair due to congenital or acquired hair shaft
abnormalities secondary to trauma or chemicals.
Its characterized clinically by unintended short hair.
Physiological Alopecia of infants, post-partum alopecia
Infections Dermatophytosis, bacterial & spirochaetal infections
Chemicals & drugs: Thallium/Heparin/cancer chemotherapy/
Trichotillomania, scratching of neurodermatitis
Endocrinopathy Hypo/ hyperthyroid, hypo/hyperparathyroid
Physical agents Mild trauma, epilating dose of radiotherapy, short term
Systemic agents SLE, dermatomyositis, sarcoidosis, Langerhan’s cell
histocytosis, amylodosis 34
Physical trauma Long term traction of hair, x-ray
Chemical injury Caustics
Cutaneous diseases DLE, FLP,pseudopelade
Destructive neoplasms &
Psychogenic conditions Neurotic excoriating tactile
injury to skin
Syn. Pelade, Area Celsi
Chronic inflammatory dermatologic disorder
characterized by patchy loss of hair without
Described by Cornelius Celsus (AD 14-37)
Term was coined by Sauvages in 1760
1. MHC class I antigen HLA-DR4, DR 11 & DQ-3
2. DR4 & DR5 – ass. with severe type of AA.
3. TNF alpha has inhibitory effect on hair growth.
4. Chromosome 21
5. Atopy – early age onset & severe AA
1. Ass. – thyroid disease, anemia, DM, vitiligo, psoriasis.
Smooth, localised, well demarcated patches
Single / multiple
Scalp (90%), other regions also involved
Hairs are short, easily extractable broken ones,
called “exclamation mark” seen at margins
1 – 5 % of AA AT – 2 yrs
White hair- relatively spared, hence patients with
canitis, the onset of sudden diffuse A.A may result in hair
‘ going white’ over night.(canites subita)
Shuster described Coudability hairs ( a kink in the
normal looking hairs, 5-10mm above the surface ,when
the hair is bent inwards).
Other immune disease
Family H/o AA
Excessive hair loss
Poor patient compliance
Hair – Pull test
Hair pluck test
SALT score ( severity of alopecia tool score)
Optical Coherence Tomography- detect hair
Peribulbar and intrabulbar inflammatory infiltrate
concentrated in and around hair bulb giving “swarm
of bees” appearance.
Infiltrate mostly of T lymphocytes and macrophages
present around the matrix and dermal papilla.
Miniaturization of hair follicles.
1. Hydrocortisone acetate 25mg/mL
2. Triamcinalone acetonide 5-10mg/mL
3. Accelerates regrowth
4. SE- Atrophy,pain,tingling - reversible
1. .25%-.1% used
2. SE-irritation, scaling, folliculitis, stains
3. 1st line Rx in children
4. Growth occurs in 3mths
5. Total application time 6mths
Alopecia totalis treated with topical immunotherapy (2,3-
diphenylcyclopropenone): (A) before treatment; (B) unilateral
hair regrowth after 15 weeks of unilateral treatment; (C)
complete regrowth after 42 subsequent weeks of bilateral
treatment. Courtesy of R Happle, University of Marburg, Marburg, Germany63
The term Telogen effluvium –first coined by Kligman.
Telogen hair- resting hairs with non pigmented club tip at
the proximal root & easily plucked from the scalp.
In this cond. premature covertion of anagen hair to
telogen hair takes place resulting in disproportionate
shedding & dec. in the total number of hair.
1. Physiologic effluvium of new born
2. Postpartum effluvium
3. Early changes of androgenic alopecia
4. Injury/ stress
5. High or prolonged fever
6. Severe infection
7. Severe chronic illness
8. Severe psychologic stress
9. Major sugery
10. Hypothyroidism & other endocrinopathies
11. Severe dieting or malnutrition
Detailed patient history (drug/diet)
Complete blood count
Hair –pull test
Sr. Zinc levels
Normal hair growth occurs with time & resolution of
No specific treatment – required
In case of no recovery – minoxidil can provide some
Androgenic alopecia is hereditary thinning of the hair
caused due to androgens in genetically susceptible men
In males, male pattern hair loss / common baldness.
In females, female pattern hair loss.
MPHL- easily recognized
1. Described – Hamilton & Norwood
2. Thinning of hair in frontal & vertex area with
progression of hair loss
3. Marginal parietal & occipital hair – retained.
FPHL- differ from men.
1) Described by Ludwig
2) Diffuse thinning over the crown with no H/O
3) In women, hair thinning begins – frontal & later
involve the entire scalp sparing the frontal hairline.
4) Hair density remains the same, hair no longer grows
into its previous length.
Hair Loss Severity Classification
For MPHL, Norwood/ Hamilton scale
For FPHL, Ludwig’s classification scale
Marked reduction in terminal hairs
Miniaturization of hair follicles increase in secondary
Mild perifollicular infiltrate mostly lymphohistiocytic
with or without concentric layers of perifollicular
Evaluation of Hair loss
History & Examination
1. Time period of hair loss(congenital, acquired)
2. Progression of hair loss
3. Any positive family history
4. H/o G.I dysfunction, thyroid gland dysfunction
, psychological disorders
5. H/o any surgical intervention / chronic illness
6. All medications
7. In females, menstrual & obstetric history
8. Hair care routine/ hair products
Physical appearance of hair and pattern of hair loss
helps in diagnosis of possible etiology.
Disease Common pattern seen
Diseases with patterned loss
Androgenic alopecia Women – central thinning
Men -- ‘M’ shaped thinning
Syphilis ‘Moth eaten ‘ appearence
Trichotillomania Bizarre, incomplete thinning ,stubble
Diseases with diffuse hair loss
Alopecia universalis Body & scalp involved
Telogen effluvium alopecia totalis , chemotherapy
or drug induced metabolic disorders
Diseases with focal loss
Alopecia areata Patchy hair loss
Tinea capitis Fragile & easily broken hair
Trichotillomania Patchy, incomplete thinning with
Traction alopecia Frontal & temporal loss of hair
Cicatricial alopecia Presence of cellulitis or folliculitis81
Complete blood count
Total iron binding capacity
Antinuclear factor –DLE
Head shots taken at a short distance away from the
patient who is seated in front of a plain cloth.
Standard global views- vertex, midline, frontal, temporal.
GB’s – taken before and at various stages of treatment
Rating – 7 point scale (-3 to +3)
Macrophotographs – 4 times magnification
_ density & diameter of hair
Area 14mm x 13mm
Density graded 1 to 6
1- fewer than 4 hairs
6- more than 40 hairs
Diameter graded 1 -thin
Regional Hair pattern
The pattern of hair loss in androgenic alopecia is
well defined & distinct in both men and women.
Norwood – Hamilton scale - male
Ludwig scale - female
Norwood-Hamilton scale of male
Contrasting Felt Examination
AIM- To see the short, miniature hairs of the scalp.
PROCEDURE- An index card with black felt glued
on one side and white felt on the opposite side is
After parting in the hair, the index card is held
along the scalp
INFERENCE- Fine short
hairs with broken or tapered
distal tips project up along
the edge of the felt.
These miniature hairs –
in the androgen dependent
areas both men & women.
Daily Hair Counts
Useful for quantitative assessment of the actual number of
hairs shed daily in patients with complaints of excessive
Collect for 14 consecutive days
Average daily loss – 30-70 hairs /day.
If >70 hairs – microscopic examination is done to
Hair Pull Test
Hair Feathering Test
Trichogram( Hair Pluck Test)
Unit Area Trichogram
Phototrichogram & Videotrichogram
Digital Epiluminescence Microscopy
Global Photographs in Phototrichogram
Telogen hair is easily extracted than anagen hair
1. About 60 hairs- pulled with constant traction
2. Bulb of extracted hair is examined
3. The number of telogen hair is counted
4. Expressed as percentage of total hair pulled
Upto 7% - normal
>10% - effluvium
Telogen effluvium, anagen effluvium, loose anagen syndrome,
early cases of patterned alopecia and the advancing edge of
Other drawbacks of this test:
Washing hair before- may give false low No. of telogen hair.
Frequency of telogen shedding varies day to day.
Seasonal variation – inc. spring & autumn.
More in the frontal & vertex region compared to occipital
Alopecia - failure of development of new anagen hair rather
than increased telogen hair ratio. In these patients hair pull
test is normal.
Hair Feathering Test
AIM- detecting abnormal hair fragility and hair shaft
1. Distal 2 to 3cm – hairs in involved areas – grasped &
2. Grasped hair - checked for broken fragments
3. Microscopic examination- confirms nature of hair
shaft defect & type of fracture.
The plucked hairs are arranged side by side
on a glass slide and taped
Anagen hair - forcibly
plucked terminal anagen
hair showing the pigmented
bulb with 'hockey-stick'
Telogen hair - forcibly plucked
early telogen hair showing the
with remanents of the cornified
Unit Area Trichogram
In a marked out area (30mm2) – hair is epilated- the
proportion of various type of hair is counted.
A/T ratio, shaft diameter, density.
Av. diameter – healthy hair- ≥ 80μ𝑚.
Phototrichogram was introduced by Saitoh in
Technique that allows in vivo study of physiology
of the hair cycle and measurement of various hair
These variables are:
1. Hair density
2. Hair thickness
3. Hair length
4. Linear growth rate.
Day 0 t(0) -Clipping the hair short (1mm) in a marked
Photograph is taken- high magnification
Day 2 (t2)
After 48 h, the second photograph was taken
Patient advised – not to wash hair
1. Hair variables at Day 0
Density of hair in the specified area
Length of hairs (L1)
2. Hair variables at Day 2
The length of hairs (L2)
Hair growth in mm/day, (L2-L1)/2
Number of hairs showing hair growth.(Anagen hairs)
Number of hairs not grown. (Telogen hairs)
Main actions of Minoxidil on the hair follicle;
1. Inc. in the proportion of hair - anagen phase by promoting
premature entry of the hair follicle into the anagen phase
2. Prolongs the length of anagen phase
3. Dec. the no. of follicles – telogen phase
4. Inc. – hair follicle size & hair diameter
On topical application- rapid inc. of hair growth is seen as soon as
6 to 8 weeks & max. effect at 12 to 16 weeks.
It’s a competent & specific inhibitor – type II 5α-reductase
90% of circulating drug bound to plasma protein.
Crosses the BBB.
Metabolized in liver, via cytochrome P450 enzyme.
Metabolites formed in liver –excreted in faeces with 40%
Indications & Dosage
Androgenic alopecia with mild to moderate hair loss
of vertex & ant. mid scalp area.
Its effectiveness in bitemporal recession has not been
Recommended dosage- 1mg orally OD daily use ≥3
Withdrawal of drug – revesal effect in 12 months.
Breast tenderness & enlargement
Pruritus, rash, urticaria , swelling of lips &
face, testicular pain.
In women- child bearing group & pregnant women
In patients hypersensitive to drug.