• Function
• Structure
• Content (Cell)
• Appendage
Integumentary System
龔秀妮
1
2 m2 / 4-5kg
Integumentary System
Functions of integumentary system
• barrier (bacteria and water)
• immunological function
• homeostasis
• sensory
• endocrine
• excretion
2
Integumentary System
E: Free nerve endings
Avascular
Skin (Cutis, integument)
• Epidermis (rete ridges)
• Dermis (dermal ridge)
• Hypodermis : adipose tissue
(subcutaneous fascia)
Epidermal derivatives of skin
Hair follicle and hair
Sweat (sudoriferous) glands
Sebaceous glands
Nails
Mammary gland
3
Layers of Skin
Epidermis :
• Stratum basale
(germinativum)
stem cells
•
•
•
Stratum spinosum
Stratum granulosum
Stratum lucidum
thick skin only
Stratum corneum
Dermis:
• Papillary layer
• Reticular layer
•
4
2011/11/01
Layers of Epidermis
Stratum Basale
(cuboid/columnar) –
Mitotic
Basophilic (rER, ribosomes)
Hemidesmosome
focal adhesion
5
SS: stratum spinosum
SB: stratum bsale
CT: connective tissue
Layers of Epidermis
Stratum spinosum
(Prickle cells) (Keratinocyte)
Tonofilaments /tonofibrils –
(eosinophilic) & lamellar body
Cytoplasmic processes
Desmosomes –
node of Bizzozero
6
2011/11/01
Layers of Epidermis
Stratum granulosum
• May be missing or discontinuous
in thin skin
• Most superficial cells of noncornified part of skin
Keratohyalin granules
(basophilic)
• Keratin filaments
• Trichohyalin Intermediate
filament associated
• Filaggrin
protein
Lamellar Body
7
Layers of Epidermis
Stratum corneum
Flattened cornified cells
• Terminally differentiated
cells
• No nucleus
• No organelles
Thick plasma membrane
Keratin filaments
• Retain cell membrane
and desmosomes in
lower layers
Cornified cells desquamate
from the outermost layer
8
Stratum lucidum
Clear, translucent (refractile) layer
Eosinophilic cells with disrucpture
nucleus and organelles
Flattened anuclear cells
Disappearance of organelles
Eleidin (semifluid)
thick skin only
1. Papillary layer: fine collagen fiber; small bv & nf
(neurovascular bundle); Messiner’s corpuscle
Dermis
2. Reticular layer: coarse collagen fiber (in bundle); elastic
fiber; dense ct; neurovascular bundle
9
Cells of Epidermis
Keratinocytes
Melanocytes
Langerhans’ cells
Merkel’s cells
10
Mixture of glycosphingolipids,
phospholipids and ceremides(神
經醯胺) secreted by exocytosis to
the intercellular space between
stratum corneum and stratum
granulosum
• To form lipid envelope of
water barrier
Keratohyalin granules
Combination of tonofibrils and
keratohyalin elements
(flaggrin and trichohyalin)
(intermediate filament associated protein)
• soft keratin of skin.
11
5nm
Lamellar bodies
insoluble protein/ 15nm
Keratinization (cytomorphosis)
12
KG: keratohyalin granules;
Arrowheads: lamellar bodies
The Life of Keratinocytes
Formation of epidermal
water barrier: cell
envelope and lipid
envelope
Cell Death :
Rupture of lysosomal
enzyme beginning
from uppermost layer
of stratum granulosum
Loss of nuclei
Complete loss of
desmosomes and
internal structures
13
2011/11/01
LEKTI
( Lympho-epithelial Kazal
Type Inhibitor) –
Prevent desmosomal
cleavage.
(keratohyalin granules + tonofilament)
(intermediate filament / tonofilament)
tonofibrils
14
Desquamation of surface
keratinocytes –
continuous exfoliation
Proteolytic degradation of
desmosome
KLK5, KLK7, KLK 14
Kallikrein-related serine peptidase
Cells of Epidermis
Keratinocytes
Melanocytes
Langerhans’ cells
Merkel’s cells
15
G
Cells in epidermis
Melanocytes
S
Neural crest origin
Dendritic in shape
No desmosomes
Cytoplasmic processes
B
between keratinocytes in
stratum spinosum
1:4 ~ 1:10 basal keratinocytes
Epidermal-melanin unit
Melanin synthesis
Pale cytoplasm, elongated
nucleus
16
premelanosome
Premelanosomes/Melanosome
membrane bound oval granules
Melanin formation:
Tyrosine
tyrosinase
DOPA
mature melanosome
17
(dihydroxyphenylalanine)
oxidization
polymerization
Melanin (against UV)
2011/11/01
Pigment donation
Melanin in melanosome
is transferred via long
processes to neighboring
keratinocytes
(pigmentation donation)
Cytocrine secretion:
including phagocytosis of
tip of melanocytosis
process
Ultraviolet light :
greater melanin formation
thickening of keratin layer
18
Cells of Epidermis
Keratinocytes
Melanocytes
Langerhans’ cells
Merkel’s cells
19
Langerhans cells
Derived from precursor in bone
marrow
3-8% of the cell population,
upper layers of stratum
spinosum
Pale clear cytoplasm and
irregular nucleus
Lack of keratin filaments
Absence of desmosomes
Participating in
antigen presenting
Containing surface receptor
similar to macrophage : MHCI,
MHCII, and Fc receptor
20
L: Langerhans cell
CP: cytoplasmic process of Langerhans cell
Arrow: melanin granules in keratinocytes
21
Langerhans cells
Birbeck granules –
“racket”-like cytoplasmic
granules
Rod with cross striation;
one end with distended
vesicle
CD1 α
22
Cells of Epidermis
Keratinocytes
Melanocytes
Langerhans’ cells
Merkel’s cells
23
Merkel’s Cell
24
Neural crest origin
Scattered in basal layer
Tactile cells (mechanoreceptor) associated with
nerve endings in papillary dermis
Cytoplasm: 80nm dense-cored granules
Merkel disc
Tactile disc
D: dermis
NT: nerve terminal
25
Cells of Epidermis
Keratinocytes
Melanocytes
Langerhans’ cells
Merkel’s cells
26
Structures in Dermis
Hair
Gland
Nail
Nerve (sensory)
27
Hair
Distribution-Sex hormone
Body temperature regulation
28
Hair
Hair shaft
•
Hard keratin from
the epithelium of
hair follicle
soft keratin:
epidermis , no
desquamation
•
Hair follicle
hair production
and growth
Appendages
•Arrector pili muscle
•Sebaceous gland
29
Hair Shaft
Medulla
central core
soft keratin
Cortex
hard-keratinized cell
melanin pigment
Cuticle
outermost layer
Hair cuticle
30
Hair follicle
Bulb
Matrix: matrix cells
(germinative layer of hair
follicle)
Dermal papilla : vascularized
connective tissue
Internal root sheath:
derived from matrix cells
covering deep part of the hair
up to opening of sebaceous
gland
External root sheath:
downward extension of
epidermis hair
Connective sheath
31
2011/11/01
Pilosebaceous canal
Inferior segment
Hair follicle
32
Hair follicle (longitudinal section)
M:medulla
Cx:cortex
Cu:cuticle
IRS: internal root sheath
ERS: external root sheath
CT:connective tissue sheath
GM:glassy membrane
DP:dermal papilla
33
Hair follicle (cross section)
He
Hu
34
S: collagen root sheath
connective tissue sheath
G: glassy membrane:
basement membrane of ERS
E: external root sheath
I: internal root sheath
Henle’s layer
Huxley’s layer (tricohyaline)
Cuticle layer
Hair shaft:
Cu: cuticle
Cx: cortex
Medulla (maybe absent)
Hair Bulb
5
Matrix : germinal layer into root
sheaths and hair shaft
Melanocytes in matrix
Dermal papilla of hair follicle
(HP): vascularized c.t. (+
sensory nerves)
35
4
3
2
1
The Hair Growth Cycle
90%
1%
Hair follicles grow in
repeated cycles. One
cycle can be broken down
9% into three phases.
1. Anagen - Growth Phase
2. Catagen - Transitional
phase
3. Telogen - Resting Phase
36
No duct
Eccrine
hormone
sweat gland
Lactating
sebaceous
sweat gland gland (skin)
Unicellular
Goblet cells
Multicellular
Exocrine (intra-, epithelial)
Simple gland
Compound gland
merocrine, apocrine, holocrine
serous, mucous, mixed
Paracrine
37
Endocrine
Tubular gland
Acinar gland
Glands of the Skin
Glandular (secretory)
part:
in dermis/hypodermis
Extension of epithelium
Types
Sebaceous gland: into
hair follicle (Holocrine)
Sweat gland
• Eccrine (Merocrine) :
into epidermis
• Apocrine: into hair
follicle
38
Pilosebaceous canal
tubule
secretory
Sebaceous gland
G:sebaceous gland
F: hair follicle
M: arrector pilli muscle
Smooth muscles
Attached to hair follicle
below sebaceous
gland
Attached to dermal
papilla
39
Sebaceous gland
Holocrine gland
Derived from external root sheath
Sebum
Duct: stratified epithelium
(pilosebaceous canal)
■ peripheral (basal) cell:
undifferentiated, round
nuclei, ER, Golgi
■ toward center:
large, lipid droplets
■ near the duct:
pyknosis of nuclei, cells
disintegrate into duct
40
Sebaceous
gland
G: sebaceous gland
within the same
sheath (membrane)
surrounding hair
follicle
Glandular portion:
Derived from external
root sheath
M: arrector pilli
muscles
F: hair follicle
41
Sebaceous glands
1. G: sebaceous gland
Within the same sheath
(membrane) surrounding
the hair follicle
2. Glandular portion:
derived from external
root sheath
M: arrector Pili
F: Hair follicle
42
Sweat Gland: secretory portion; duct portion
Eccrine (Merocrine) sweat gland
in most parts of the body
open through epidermis
independent of hair follicle
sympathetic cholinergic
innervation
Apocrine sweat gland
in axilla, perianal/perigenital
areas, mammary areola,
ceruminous glands in external
auditory canal, glands of Moll
in eyelashes
open through hair follicle (above
sebaceous gland)
sympathetic adrenergic innervation
43
Eccrine (Merocrine) sweat gland
Secretory component:
pseudostratified (simple)
cuboid/columnar epi.,
pale-stained,
pyramid cells on basement membrane
EM- light cells: pumping Na+ into lumen
- dark cells: secreting glycoprotein
Myoepithelial cells: actin filament
(eosinophilic) for contraction to expel sweat
Excretory duct:
narrower lumen than secretory part
stratified (double) cuboid
no myoepithelial cells
spiral course, end in epidermis
44
45
Merocrine
(Eccrine) Sweat
gland: EM
Clear Cells (C) :
glycogen; mainly
facing intercellular
canaliculus (IC)
Dark cells (D) :
secretory granules;
mainly facing lumen
(L)
Myoepithelial
cells (My): on the
basement
membrane
46
Merocrine (eccrine) sweat glands
Clear cell (C): glycogen,
infolding of membrane,
mitochondria, water, pump Na+
into lumen
Dark cell (D): rER, secretory
granules, Golgi (G),
glycoprotein
Myoepithelial cells (My):
contractile actin filaments,
under autonomic control, help
to expel secretion
Secretion: water, NaCl, urea,
ammonia, uric acid
47
Apocrine sweat glands
Secretory portion:
coiled tubular glands
dilated lumen
low cuboid
eosinophic cytoplasm
“apical budding”
discontinuous layer of
myoepithelial cells above
basement membrane
Excretory duct:
secretion into near-by hair follicles
Secretion: protein rich, CHO, NH3,
lipid (pigmented)
Mature after puberty
48
49
Mammary gland
50
Nail
51
2015/10/13
Nail
Nail plate (Nail):
hard keratin (similar to hair cortex)
high sulfur content
Nail bed:
underlying epithelia
continuous with SB and SS
Nail root:
proximal part of nail plate
Nail matrix:
germinative zone
Eponychium (cuticle):
edge of skin covering nail root
Hyponychium:
epidermis underlying free edge of nail
plate
52
Nerve
Motor-autonomic nerve
blood vessels
arrector pili muscle
sweat gland
Sensory
53
1. Free nerve
ending
Nerve (Sensory)
Merkel’s disk
2. Pacinian
corpuscle
pressure
4. Ruffini’s
corpuscle
heat
3. Meissner’s
corpuscle
touch
54
touch
pressure
Ruffini’s
corpuscle
heat
55
Sensory
56
Wound healing
58
Pathology
Burns
Anterior values
1st degree burn
Totals
41⁄2%
Anterior and posterior
head and neck, 9%
Anterior and posterior
upper limbs, 18%
2nd degree burn
41⁄2% Anterior 41⁄2%
(a)
Skin bearing partial thickness burn
(first- and second-degree burns)
trunk, 18%
Anterior and posterior
trunk, 36%
9%
(Perineum, 1%)
3rd degree burn
9%
Anterior and posterior
lower limbs, 36%
100%
(b) Skin bearing full thickness burn
(third-degree burn)
(c)
Rule of nines; used to estimate
extent of burns
Figure 5.10
Skin Cancer
Figure 5.11
Malignant melanoma lesion in the early
stage of radial growth phase
61
Malignant melanoma during radial
growth phase
Summary
Skin (Cutis, integument)
• Epidermis – stratum corneum, lucidum, granulosum,
spinosum, basale
• Dermis – papillary layer (Meissner’s corpusccle), reticular
layer
• Hypodermis (subcutaneous fascia) – Paccian corpuscle,
Epidermal derivatives of skin
• Hair follicle -- ct sheath, ERS, IRS, (cuticle), hair shaft,
hair bulb, dermal papilla; Huxley layer, Henle’s layer, matrix
• Sweat (sudoriferous) glands –secretory segment, duct
segment, Myoepithelial cells
Merocrine (eccrine); apocrine
• Sebaceous glands – apocrine
•Arrector pili – smooth muscle
• Nails – dermal ridge, epo- & hyponychium
62• Nerve – motor, sensory
2011/11/01