Download Lab 11 – Skin (Integument)

Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Introduction
Skin (Integument)
Learning Objectives
Keywords
Slides
A. Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
SEM of hair shafts emerging from skin.
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Introduction
Learning Objectives
Keywords
Slides
A. Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
Learning Objectives
1. Understand the functions and physiological importance of the skin.
2. Know the layers of the epidermis and their cellular characteristics.
3. Recognize melanocytes and understand their function and mechanism of
action.
4. Understand the structure, function, and formation of specialized features
of the integument: hair, nails, sweat and sebaceous glands.
5. Know the cellular and extracellular composition of the dermis.
6. Know the sensory specializations of the skin.
7. Understand the basic mechanism of epidermal/dermal repair and
regeneration.
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Introduction
Keywords
Slides
A. Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
Keywords
Learning Objectives
b. Apocrine
D. Nails
Summary
Apocrine sweat gland
Arrector pili muscle
Dermal papillae
Dermis
Epidermis
External root sheath
Follicle cortex
Follicle cuticle
Follicle medulla
Hair follicle
Internal root sheath
Keratinocyte
Meissner’s corpuscle
Melanocyte
Merocrine sweat gland
Myoepithelial cell
Nail
Pacinian corpuscle
Papillary layer
Reticular layer
Sebaceous gland
Stratum basale
Stratum corneum
Stratum granulosum
Stratum lucidum
Stratum spinosum
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Introduction
Learning Objectives
Slide 138: Eyelid, H&E
Keywords
Slides
A. Skin
1. Thick vs. Thin Skin
looking at the slides of the eyelid and the lip,
determine which of the surfaces is covered in
skin and which is covered in conjunctiva or oral
mucosa, respectively
Slide 119 (NW): Lip, Sagittal Section
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
Slide 89: Thick Skin, Trichrome
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
look at different slides of skin to appreciate the
differences in appearance of thick vs. thin skin
and in H&E vs. trichrome stains
Lab 11 – Skin (Integument)
III.
IV.
Introduction
Learning Objectives
Keywords
Slides
A. Skin
Slide 36 : Thin Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
epidermis
II.
Slide 83 (464): Thick Skin
epidermis
I.
IUSM – 2016
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
Thick Skin
Thin Skin
1.
Found on soles, palms and fingertips
1.
Majority of skin
4.
Hairless (glabrous)
4.
Pilosebaceous units (hair follicles)
2.
3.
“Thick” epidermis: 400-1400μm
5 layers of epidermis (Stratum lucidum)
2.
3.
“Thin” epidermis: 75-150μm
4 layers of epidermis
skin is classified as either thick or thin based upon the thickness of the epidermis: thin (hairy) skin covers the
majority of the body and thick (glabrous) skin is generally restricted to the palm of the hand and sole of the
foot; however, this classification ignores the thickness of the dermis (and therefore the actual “thickness” of
the skin) – thus, the skin on the upper back is classified as “thin” based upon its epidermis, but is actually
some of the thickest skin in the body based upon the combined thickness of the epidermis and dermis
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Introduction
Learning Objectives
Keywords
Slides
A. Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
Slide 83 (464): Skin of Sole, H&E
epidermis
epithelial compartment of the skin, consisting of
keratinized stratified squamous epithelium
dermis
connective tissue compartment of the skin,
underlying the epithelium; it provides support and
nourishment of the epidermis and contains
vasculature, skin appendages, and sensory
receptors
hypodermis
also known as subcutaneous tissue or superficial
fascia; the layer is not technically considered a
layer of the skin, rather it is a deep connective
tissue layer, with varying amount of adipose, that
serves to anchor the skin (dermis) to underlying
structures (e.g., muscle)
Lab 11 – Skin (Integument)
II.
III.
IV.
Slide 72 (NW): Thick Skin
Introduction
Learning Objectives
Keywords
Slides
A. Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
epidermis
I.
IUSM – 2016
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
dermis
stratum corneum: the most superficial layer of the
epidermis; consists of dead, flattened, anucleate
keratinocytes that form “water barrier”; it is generally
20-30 cell layers thick but varies depending upon
location and is much more prominent in thick skin than
in thin skin; skin on the genitals has the fewest layers
(~5) while skin on the heel has the most (~100)
stratum lucidum: present in thick skin only
stratum granulosum: 3-5 layers of cells; cells are
undergoing keratinization which takes 2-6 hours
stratum spinosum: thickest “cellular layer” of the
epidermis; on higher magnification, keratinocytes
have a “spiny” or “prickly” appearance; Langerhans
cells are also present
stratum basale: single-cell layer of mitotically-active
keratinocytes, melanocytes, and Merkel cells
mnemonic for the layers of the epidermis, from most superficial to deepest: come, let’s get sun-burned
(terrible advice but a helpful mnemonic)
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Introduction
Learning Objectives
Keywords
Slide 5: Thick Skin, Trichrome
Slides
A. Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
Slide 36: Thin Skin, H&E
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
the stratum spinosum is the thickest cellular
layer of the epidermis; it consists principally of
keratinocytes with a few interspersed Langerhans
cells (antigen-presenting cells) which are
generally not readily identifiable on routine slide
preparations
notice the very fine spines (at arrow tips)
from the desmosomes connecting the
keratinocytes together, giving them a
“prickly” or “spiny” appearance
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
Slide 36: Thin Skin, H&E
IUSM – 2016
Introduction
Learning Objectives
Keywords
L
Slides
A. Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
L
stratum
spinosum
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
M
M
stratum
basale
papillary layer
of dermis
M
melanocytes (M) are found in the stratum basale (and in hair follicles), with approximately one melanocyte
for every 5-6 keratinocytes; they have pale-staining, rounded cell bodies and cytoplasmic extensions up into
the stratum spinosum; they are responsible for the production of brownish-colored melanin pigment (blue
arrow); also, possible Langerhans cells (L) may be seen – they have a dark-staining nucleus and light-staining
cytoplasm with numerous cytoplasmic extensions (difficult to visualize in routine preparations); they are
antigen-presenting cells found primarily in the stratum spinosum
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Introduction
Learning Objectives
Keywords
Slides
A. Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
Slide 73 (NW): Thin Skin, Pigmented
the “flakiness” of the stratum
corneum is an artifact of slide
preparation
lots of granules of
melanin pigment
1. Pilosebaceous units
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
the difference in skin color between individuals is due to differences in the activity level of melanocytes, not
differences in the relative number of melanocytes which are roughly 5% of the total cells of the epidermis
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Introduction
Learning Objectives
Keywords
Slides
A. Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
Slide 5: Thick Skin, Trichrome
dermal papilla
(dermis)
rete (ree-tee) ridge
(epidermis)
papillary
layer
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
reticular
layer
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
the dermis is composed of the more superficial papillary layer directly underlying the epidermis and the
deeper reticular layer; the papillary layer is composed of loose CT and forms upward-projecting dermal
papillae that interdigitate with downward-projecting rete ridges of the epidermis to “anchor” the epidermis to
the dermis and resist frictional forces; the reticular layer contains dense irregular CT surrounding skin
appendages (e.g., hair follicles and sweat glands); note that there is no sharp demarcation between the two
specific layers so defining the transition area between them is arbitrary
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Introduction
Learning Objectives
Keywords
Slides
Slide 72 (NW): Thick Skin
epidermis
A. Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
hypodermis
(subcutaneous tissue or superficial fascia)
contains a varying amount of adipose tissue but overall
accounts for nearly 50% of the body’s total fat storage;
the extensive vascular supply within the layer allows
for rapid uptake of drugs, making this a common site
for medication (e.g., insulin) injections
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Introduction
Learning Objectives
Keywords
Slides
A. Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
Slide 60 (NW): Fingertip
look in the dermal papillae
(papillary layer of dermis) to
find Meissner’s corpuscles
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
look in the deep dermis
and hypodermis to find
Pacinian corpuscles
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Introduction
Learning Objectives
Keywords
Slides
A. Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
Slide 60 (NW): Fingertip
b. Apocrine
D. Nails
Summary
Pacinian (lamellated) corpuscles
are large, pressure and vibration
receptors found within the dermis
and hypodermis; seen in crosssection, they have a “cut onion”
appearance of concentric layers
(lamellae) of Schwann cells and
collagen fibrils surrounding a
central axon
eccrine sweat gland
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Introduction
Learning Objectives
Slide 61 (NW): Pacinian Corpuscle
Keywords
Slides
A. Skin
a large Pacinian corpuscle seen in
longitudinal section
Slide 12: Urinary Bladder, Cat
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
Slide 5: Thick Skin, Trichrome
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
Pacinian corpuscles can also be found
associated with joints, periosteum, and
internal organs
look here, deep in the hypodermis, to find
additional examples of Pacinian corpuscles
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Introduction
Learning Objectives
Keywords
Slides
A. Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
Slide 60 (NW): Fingertip
b. Apocrine
D. Nails
Summary
Meissner’s (tactile) corpuscles
are receptors for light touch
found in dermal papillae
(not seen in every papilla);
they are oval shaped with
stacked Schwann cells
surrounding a central nerve
fiber; elongated nuclei of
fibroblasts wrapping
transversely around and
providing a connective tissue
capsule may be visible
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Slide 51: Thin Skin, H&E
Introduction
Learning Objectives
Keywords
Slides
A. Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
a. Hair follicle
hair follicle
sebaceous
gland
arrector
pili m.
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
a pilosebaceous unit (Lt. “hair and tallow”) consists of three major structures: a hair follicle (and hair),
associated sebaceous glands, and an arrector pili muscle; the hair follicle and sebaceous glands are both
derived from downgrowths of the epithelium of the epidermis, while the arrector pili m. is smooth muscle
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Slide 67: Lip, H&E
Introduction
Learning Objectives
Keywords
Slides
A. Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
a. Hair follicle
b. Sebaceous gland
keratinized stratified
squamous epithelium
of the skin
look here to see
examples of
hair follicles
in longitudinalsection
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
skeletal muscle of the lip
(orbicularis oris m.)
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
Slide 67: Lip, H&E
IUSM – 2016
Introduction
Learning Objectives
Keywords
Slides
A. Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
external root
sheath
1. Pacinian corpuscles
internal root
sheath
1. Pilosebaceous units
hair
(3 layers)
2. Meissner’s corpuscles
C. Skin Appendages
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
a hair follicle generally consists of five specialized layers of epithelial cells: the hair (hair shaft) itself consists
of three layers (inner medulla layer surrounded by the cortex layer and the outermost cuticle layer on the
surface of the hair); next, the internal root sheath (IRS) layer surrounds the hair at the base but does not
extend above the level of attachment of the sebaceous gland to the follicle; finally the outermost external root
sheath (ERS) layer is a direct continuation of the epidermis of the skin; the ERS is separated from the CT of the
dermal sheath surrounding the epithelial hair follicle by a thick basement membrane (the glassy membrane)
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Slide 17: Thin Skin, Trichrome
Introduction
Learning Objectives
Keywords
Slides
A. Skin
epidermis
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
look here to see
examples of
hair follicles
in cross-section
dermis
hypodermis
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
skeletal
muscle
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Introduction
Learning Objectives
Keywords
Slides
A. Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
Slide 17: Thin Skin, Trichrome
dermal connective tissue
sheath surrounds follicle
glassy membrane
(basement membrane)
between ERS and dermal CT
external root sheath (ERS)
internal root sheath (IRS) is
darker-staining and consists
of three specific sublayers
(cuticle, Huxley, Henle)
cortex of hair
(medulla is not visible)
cuticle of hair
similar to thick skin which has five layers of epidermal epithelium, a hair follicle
consists of five specialized layers of epithelium (medulla, cortex, cuticle, IRS, ERS)
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Introduction
Learning Objectives
Keywords
Slides
A. Skin
Slide 51: Thin Skin, H&E
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
hair within the
pilosebaceous canal
of the hair follicle
sebaceous glands
are simple, branched
acinar glands
sebaceous glands are glandular epithelial outgrowths generally associated with the external root sheath of
hair follicles; the sebocytes of the glands undergo holocrine section, releasing sebum and cellular debris into the
hair follicle; sebocytes contain large amount of lipid and abundant smooth endoplasmic reticulum (sER), giving
them a characteristic pale-staining appearance
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Introduction
Learning Objectives
Keywords
Slides
A. Skin
Slide 138: Eyelid, H&E
skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
sebaceous gland surrounding
a hair follicle in the skin
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
Meibomian (tarsal) glands are
specialized sebaceous glands associated
with the conjunctiva of the eyelid
conjunctiva
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Slide 138: Eyelid, H&E
Introduction
Learning Objectives
Keywords
Slides
A. Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
Meibomian
glands
C. Skin Appendages
1. Pilosebaceous units
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
conjunctiva
stratified columnar
epithelium
Meibomian glands are specialized sebaceous glands that empty directly onto the epithelial surface of the
eyelid, instead of into a hair follicle; they produce an oily product onto the tear film of the eye which serves to
slow tear evaporation
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
Slide 51: Thin Skin, H&E
IUSM – 2016
Introduction
Learning Objectives
Keywords
Slides
A. Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
hair follicle
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
arrector pili
muscle
sebaceous
gland
arrector pili muscles (Lt. “raiser of hair”) are small bundles of smooth muscle attached to the connective
tissue sheath of the hair follicle and inserting into the CT of the dermal papillary layer; contraction of the
muscle, via innervation of the sympathetic nervous system, leads to erection of the hair shaft and can be seen
as “goose bumps” as the contracted muscle distorts the shape of the dermis
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Introduction
Learning Objectives
Keywords
Slides
A. Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
Slide 36: Thin Skin, H&E
unbranched, dark-staining
duct portion of
eccrine sweat gland
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
highly-coiled, pale-staining
secretory portion of
eccrine sweat gland
eccrine (merocrine) sweat glands are found in most areas of thick and thin skin of the body (except lips and
parts of genitalia); they are simple, coiled tubular glands with their secretory portions generally located deep
in the dermis or into the hypodermis and their duct portions emptying onto the surface of the skin
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Introduction
Learning Objectives
Keywords
Slides
A. Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
Slide 36: Thin Skin, H&E
duct portions of the gland are darkerstaining, have a smaller lumen, and consist
of stratified cuboidal epithelium; the apical
surface is covered in microvilli and generally
stains more eosinophilic
secretory portions of the gland are lighterstaining and consists of simple cuboidal
epithelium (may appear pseudostratified)
with surrounding myoepithelial cells
myoepithelial cells are eosinophilic cells
that surround the secretory portions of the
gland (not the duct portion); they are
specialized contractile epithelial cells that
assist in “squeezing” secretory products
out of the gland
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Introduction
Learning Objectives
Keywords
Slides
A. Skin
Slide 44a (464): Skin, Axilla, H&E
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
look in the dermis and
hypodermis of the skin
from the axilla (armpit)
to see examples of
apocrine sweat glands
note that eccrine sweat
glands are also present
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
apocrine sweat glands are primarily found in the axillary and perineal regions; despite the name (a historical
misnomer), like eccrine glands they undergo merocrine – not apocrine – secretion; they appear similar to
eccrine glands except the lumens of their secretory portions are much wider; the duct portion is histologically
similar to those of eccrine glands but instead of emptying on the surface of the skin, they empty into adjacent
hair follicles
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Introduction
Learning Objectives
Keywords
Slides
A. Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
Slide 25: Auditory Meatus, H&E
keratinized stratified
squamous epithelium
hair follicle and surrounding
sebaceous glands
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
ceruminous glands are specialized
apocrine sweat glands that facilitate
production of cerumen (earwax)
the ear canal (external auditory meatus)
is the only “blind pouch” of skin in the
body and lacks eccrine sweat glands
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Introduction
Learning Objectives
Keywords
Slides
A. Skin
1. Thick vs. Thin Skin
Slide 42a (464): Fingertip, H&E
nail bed
nail plate
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
eponychium
(cuticle)
hyponychium
(high-poe-nik-ee-uhm)
Gr. –onyx = nail
“below the nail”
nail root
nail fold (skin)
bone
(phalanx)
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
there are three specialized regions of the epidermis associated with the nail: the eponychium (cuticle) is the
extension of the stratum corneum of the nail fold over the nail root, where new nail plate growth occurs; the
nail bed includes the epidermis which binds the nail plate, and the hyponychium is the epidermal fold
beneath the free edge of the distal nail plate which serves to secure the plate at the tip of the finger
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Introduction
Learning Objectives
Keywords
Slides
Slide 75 (NW): Fingertip and Nail
A. Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
nail plate
(hard keratin)
epithelium
dermis
nail
bed
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
Summary
unlike the soft keratin found in the stratum corneum of all other areas of skin, nails (or nail plates) contain
plates of hard keratin, similar to that found in the hair cortex, containing a high sulfur content; nail formation
occurs in a manner similar to hair formation with keratinocytes proliferating and differentiating in the matrix of
the nail root, at the proximal aspect of the nail; this growth causes the nail to “slide” forward across the nail bed
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
IUSM – 2016
Introduction
Summary
1.
Learning Objectives
Keywords
Slides
A. Skin
1. Thick vs. Thin Skin
2.
2. Layers
Skin is composed of all four basic tissue types (epithelium, CT, muscle, and nervous)
and is involved in a variety of body processes including protection, homeostasis, and
sensation; it covers the entire body surface area and is the largest organ of the body.
All skin consists of two layers: a superficial epithelial epidermis and an underlying
supportive connective tissue dermis.

a. Epidermis
b. Dermis
c. Hypodermis

B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
b. Apocrine
D. Nails
3.
Epidermis is avascular stratified squamous epithelium divided into four or five
specific layers (thin vs. thick skin); it consists primarily of keratin-producing
keratinocytes with interspersed melanocytes, Langerhans cells, and Merkel cells.
Dermis is connective tissue (loose CT and deeper dense irregular CT) that
accounts for the majority of the mass of the skin; it has a well-defined border with
the overlaying epidermis but lacks a defined deep border with the underlying
hypodermis; within the dermis are found most of the skin appendages,
vasculature, and sensory structures.
Skin appendages are structures derived from downward growths of the epithelium of
the epidermis; they are responsible for the production of specialized products that
serve important roles in fulfilling the overall functions of skin:


Summary

Hair follicles produce hair for protection and thermoregulation.
Sebaceous glands produce sebum for protection of skin and hair and may also
serve a role in innate immunity.
Sweat glands produce sweat for thermoregulation and sexual attraction.
Lab 11 – Skin (Integument)
I.
II.
III.
IV.
Introduction
Learning Objectives
Keywords
Slides
A. Skin
1. Thick vs. Thin Skin
2. Layers
a. Epidermis
b. Dermis
c. Hypodermis
B. Sensory Receptors
1. Pacinian corpuscles
2. Meissner’s corpuscles
C. Skin Appendages
1. Pilosebaceous units
a. Hair follicle
b. Sebaceous gland
c. Arrector pili muscle
2. Sweat glands
a. Eccrine (Merocrine)
V.
Compare and Contrast Structures of the Integumentary System
IUSM – 2016
b. Apocrine
D. Nails
Summary
Cell
Thin vs. Thick
skin
Hair follicle vs.
Nail
Pacinian vs.
Meissner corpuscles
Eccrine vs.
Apocrine glands
Papillary vs.
Reticular layers
Stratum granulosum
vs. Stratum basale
Similarities
Differences