1. Chapter Opener 4
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2. Nervous tissue: Internal communication • Brain • Spinal cord • Nerves
Figure 4.1 Overview of four basic tissue types: epithelial, connective, muscle, and nervous tissues.
Nervous tissue: Internal communication
• Brain
• Spinal cord
• Nerves
Muscle tissue: Contracts to cause movement
• Muscles attached to bones (skeletal)
• Muscles of heart (cardiac)
• Muscles of walls of hollow organs (smooth)
Epithelial tissue: Forms boundaries between different environments, protects, secretes, absorbs, filters
• Lining of digestive tract organs and other hollow organs
• Skin surface (epidermis)
Connective tissue: Supports, protects, binds other tissues together
• Bones
• Tendons
• Fat and other soft padding tissue
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3. Figure 4.2 Classification of epithelia.
Apical surface
Basal surface
Simple
Apical surface
Basal surface
Stratified
Classification based on number of cell layers.
Squamous
Cuboidal
Columnar
Classification based on cell shape.
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4. Figure 4.2a Classification of epithelia.
Apical surface
Basal surface
Simple
Apical surface
Basal surface
Stratified
Classification based on number of cell layers.
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5. Figure 4.2b Classification of epithelia.
Squamous
Cuboidal
Columnar
Classification based on cell shape.
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6. Figure 4.3a Epithelial tissues.
Simple squamous epithelium
Description: Single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasm; the simplest of the epithelia.
Air sacs of lung tissue
Nuclei of squamous epithelial cells
Function: Allows materials to pass by diffusion and filtration in sites where protection is not important; secretes lubricating substances in serosae.
Location: Kidney glomeruli; air sacs of lungs; lining of heart, blood vessels, and lymphatic vessels; lining of ventral body cavity (serosae).
Photomicrograph: Simple squamous epithelium forming part of the alveolar (air sac) walls (140x).
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7. Figure 4.3b Epithelial tissues.
Simple cuboidal epithelium
Description: Single layer of
cubelike cells with large, spherical central nuclei.
Simple cuboidal epithelial cells
Nucleus
Function: Secretion and absorption.
Basement membrane
Location: Kidney tubules; ducts and secretory portions of small glands; ovary surface.
Connective tissue
Photomicrograph: Simple cuboidal epithelium in kidney tubules (430x).
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8. Figure 4.3c Epithelial tissues.
Simple columnar epithelium
Description: Single layer of tall cells with round to oval nuclei; some cells bear cilia; layer may contain mucus-secreting unicellular glands (goblet cells).
Microvilli
Simple columnar epithelial cell
Function: Absorption; secretion of mucus, enzymes, and other substances; ciliated type propels mucus (or reproductive cells) by ciliary action.
Mucus of goblet cell
Location: Nonciliated type lines most of the digestive tract (stomach to rectum), gallbladder, and excretory ducts of some glands; ciliated variety lines small bronchi, uterine tubes, and some regions of the uterus.
Basement membrane
Photomicrograph: Simple columnar epithelium of the small intestine mucosa (660x).
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9. Figure 4.3d Epithelial tissues.
Pseudostratified columnar epithelium
Description: Single layer of cells of differing heights, some not reaching the free surface; nuclei seen at different levels; may contain mucus-secreting cells and bear cilia.
Cilia
Pseudo-stratified epithelial layer
Function: Secrete substances, particularly mucus; propulsion of mucus by ciliary action.
Location: Nonciliated type in male’s sperm-carrying ducts and ducts of large glands; ciliated variety lines the trachea, most of the upper respiratory tract.
Basement membrane
Photomicrograph: Pseudostratified ciliated columnar epithelium lining the human trachea (800x).
Trachea
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10. Figure 4.3e Epithelial tissues.
Stratified squamous epithelium
Description: Thick membrane composed of several cell layers; basal cells are cuboidal or columnar and metabolically active; surface cells are flattened (squamous); in the keratinized type, the surface cells are full of keratin and dead; basal cells are active in mitosis and produce the cells of the more superficial layers.
Stratified squamous epithelium
Function: Protects underlying tissues in areas subjected to abrasion.
Nuclei
Location: Nonkeratinized type forms the moist linings of the esophagus, mouth, and vagina; keratinized variety forms the epidermis of the skin, a dry membrane.
Basement membrane
Connective tissue
Photomicrograph: Stratified squamous epithelium lining the esophagus (285x).
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11. Figure 4.3f Epithelial tissues.
Transitional epithelium
Description: Resembles both stratified squamous and stratified cuboidal; basal cells cuboidal or columnar; surface cells dome shaped or squamouslike, depending on degree of organ stretch.
Transitional epithelium
Function: Stretches readily, permits stored urine to distend urinary organ.
Basement membrane
Location: Lines the ureters, bladder, and part of the urethra.
Connective tissue
Photomicrograph: Transitional epithelium lining the bladder, relaxed state (360x); note the bulbous, or rounded, appearance of the cells at the surface; these cells flatten and elongate when the bladder fills with urine.
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12. Figure 4.4 Goblet cell (unicellular exocrine gland).
Microvilli
Secretory vesicles containing mucin
Golgi apparatus
Rough ER
Nucleus
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13. Figure 4.4a Goblet cell (unicellular exocrine gland).
Microvilli
Secretory vesicles containing mucin
Golgi
apparatus
Rough ER
Nucleus
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14. Figure 4.4b Goblet cell (unicellular exocrine gland).
Microvilli
Secretory vesicles containing mucin
Golgi apparatus
Rough ER
Nucleus
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15. Figure 4.5 Types of multicellular exocrine glands.
Simple duct structure
(duct does not branch)
Compound duct structure
(duct branches)
Tubular secretory structure
Simple tubular Example
Intestinal glands
Simple branched tubular
Example
Stomach (gastric) glands
Compound tubular
Example
Duodenal glands of small intestine
Alveolar secretory structure
Simple alveolar
Example
No important example in humans
Simple branched alveolar
Example
Sebaceous (oil) glands
Compound alveolar
Example
Mammary glands
Compound tubuloalveolar
Example
Salivary glands
Surface epithelium
Duct
Secretory epithelium
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16. Figure 4.5 Types of multicellular exocrine glands. (1 of 2)
Simple duct structure
(duct does not branch)
Tubular secretory structure
Simple tubular Example
Intestinal glands
Simple branched tubular
Example
Stomach (gastric) glands
Alveolar secretory structure
Simple alveolar
Example
No important example in humans
Simple branched alveolar
Example
Sebaceous (oil) glands
Surface epithelium
Duct
Secretory epithelium
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17. Figure 4.5 Types of multicellular exocrine glands. (2 of 2)
Compound duct structure
(duct branches)
Tubular secretory structure
Compound tubular
Example
Duodenal glands of small intestine
Alveolar secretory structure
Compound alveolar
Example
Mammary glands
Compound tubuloalveolar
Example
Salivary glands
Surface epithelium
Duct
Secretory epithelium
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18. Figure 4.6 Chief modes of secretion in human exocrine glands.
Secretory cell fragments
Secretory vesicles
Merocrine glands secrete their products by exocytosis.
In holocrine glands, the entire secretory cell ruptures, releasing secretions and dead cell fragments.
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19. Figure 4.6a Chief modes of secretion in human exocrine glands.
Secretory vesicles
Merocrine glands secrete their products by exocytosis.
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20. Figure 4.6b Chief modes of secretion in human exocrine glands.
Secretory cell fragments
In holocrine glands, the entire secretory cell ruptures, releasing secretions and dead cell fragments.
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21. Cell types Extracellular matrix Ground substance Macrophage Fibers
Figure 4.7 Areolar connective tissue: A prototype (model) connective tissue.
Cell types
Extracellular matrix
Ground substance
Macrophage
Fibers
• Collagen fiber
• Elastic fiber
• Reticular fiber
Fibroblast
Lymphocyte
Fat cell
Mast cell
Neutrophil
Capillary
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22. Table 4.1 Comparison of Classes of Connective Tissues (1 of 2)
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23. Table 4.1 Comparison of Classes of Connective Tissues (2 of 2)
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24. Figure 4.8a Connective tissues.
Connective tissue proper: loose connective tissue, areolar
Description: Gel-like matrix with all three fiber types; cells: fibroblasts, macrophages, mast cells, and some white blood cells.
Function: Wraps and cushions organs; its macrophages phagocytize bacteria; plays important role in inflammation; holds and conveys tissue fluid.
Elastic fibers
Ground substance
Location: Widely distributed under epithelia of body, e.g., forms lamina propria of mucous membranes; packages organs; surrounds capillaries.
Fibroblast nuclei
Collagen fibers
Epithelium
Photomicrograph: Areolar connective tissue, a soft packaging tissue of the body (340x).
Lamina propria
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25. Figure 4.8b Connective tissues.
Connective tissue proper: loose connective tissue, adipose
Description: Matrix as in areolar, but very sparse; closely packed adipocytes, or fat cells, have nucleus pushed to the side by large fat droplet.
Function: Provides reserve food fuel; insulates against heat loss; supports and protects organs.
Nucleus of adipose (fat) cell
Location: Under skin in subcutaneous tissue; around kidneys and eyeballs; within abdomen; in breasts.
Fat droplet
Adipose tissue
Photomicrograph: Adipose tissue from the subcutaneous layer under the skin (350x).
Mammary glands
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26. Figure 4.8c Connective tissues.
Connective tissue proper: loose connective tissue, reticular
Description: Network of reticular fibers in a typical loose ground substance; reticular cells lie on the network.
Function: Fibers form a soft internal skeleton (stroma) that supports other cell types including white blood cells, mast cells, and macrophages.
White blood cell
(lymphocyte)
Location: Lymphoid organs (lymph nodes, bone marrow, and spleen).
Reticular fibers
Spleen
Photomicrograph: Dark-staining network of reticular connective tissue fibers forming the internal skeleton of the spleen (350x).
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27. Figure 4.8d Connective tissues.
Connective tissue proper: dense connective tissue, dense regular
Description: Primarily parallel
collagen fibers; a few elastic fibers;
major cell type is the fibroblast.
Function: Attaches muscles to
bones or to muscles; attaches
bones to bones; withstands great
tensile stress when pulling force is
applied in one direction.
Collagen
fibers
Location: Tendons, most
ligaments, aponeuroses.
Nuclei of
fibroblasts
Shoulder
joint
Ligament
Photomicrograph: Dense regular connective
tissue from a tendon (430x).
Tendon
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28. Figure 4.8e Connective tissues.
Connective tissue proper: dense connective tissue, dense irregular
Description: Primarily irregularly
arranged collagen fibers; some
elastic fibers; fibroblast is the
major cell type.
Nuclei of
fibroblasts
Function: Withstands tension
exerted in many directions;
provides structural strength.
Location: Fibrous capsules of
organs and of joints; dermis of the
skin; submucosa of digestive tract.
Collagen
fibers
Shoulder
joint
Fibrous
joint
capsule
Photomicrograph: Dense irregular connective
tissue from the fibrous capsule of a joint (430x).
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29. Figure 4.8f Connective tissues.
Connective tissue proper: dense connective tissue, elastic
Description: Dense regular
connective tissue containing a
high proportion of elastic fibers.
Function: Allows tissue to recoil
after stretching; maintains pulsatile
flow of blood through arteries; aids
passive recoil of lungs following
inspiration.
Location: Walls of large arteries;
within certain ligaments associated
with the vertebral column; within
the walls of the bronchial tubes.
Elastic
fibers
Aorta
Heart
Photomicrograph: Elastic connective tissue
in the wall of the aorta (250x).
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30. Figure 4.8g Connective tissues.
Cartilage: hyaline
Description: Amorphous but firm
matrix; collagen fibers form an
imperceptible network;
chondroblasts produce the matrix
and when mature (chondrocytes)
lie in lacunae.
Function: Supports and reinforces;
serves as resilient cushion; resists
compressive stress.
Chondrocyte
in lacuna
Location: Forms most of the
embryonic skeleton; covers the
ends of long bones in joint cavities;
forms costal cartilages of the ribs;
cartilages of the nose, trachea, and
larynx.
Matrix
Costal
cartilages
Photomicrograph: Hyaline cartilage from
a costal cartilage of a rib (470x).
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31. Figure 4.8h Connective tissues.
Cartilage: elastic
Description: Similar to hyaline
cartilage, but more elastic fibers
in matrix.
Function: Maintains the shape of
a structure while allowing great
flexibility.
Chondrocyte
in lacuna
Matrix
Location: Supports the external
ear (pinna); epiglottis.
Photomicrograph: Elastic cartilage from
the human ear pinna; forms the flexible
skeleton of the ear (800x).
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32. Figure 4.8i Connective tissues.
Cartilage: fibrocartilage
Description: Matrix similar to but
less firm than that in hyaline
cartilage; thick collagen fibers
predominate.
Function: Tensile strength allows
it to absorb compressive shock.
Location: Intervertebral discs;
pubic symphysis; discs of knee
joint.
Chondrocytes
in lacunae
Intervertebral
discs
Collagen
fiber
Photomicrograph: Fibrocartilage of an
intervertebral disc (125x). Special staining
produced the blue color seen.
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33. Figure 4.8j Connective tissues.
Others: bone (osseous tissue)
Description: Hard, calcified
matrix containing many collagen
fibers; osteocytes lie in lacunae.
Very well vascularized.
Function: Supports and protects
(by enclosing); provides levers for
the muscles to act on; stores
calcium and other minerals and
fat; marrow inside bones is the
site for blood cell formation
(hematopoiesis).
Central
canal
Lacunae
Lamella
Location: Bones
Photomicrograph: Cross-sectional view
of bone (125x).
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34. Figure 4.8k Connective tissues.
Connective tissue: blood
Description: Red and white blood
cells in a fluid matrix (plasma).
Red blood
cells
(erythrocytes)
Function: Transport respiratory
gases, nutrients, wastes, and other
substances.
White blood
cells:
• Lymphocyte
• Neutrophil
Location: Contained within blood
vessels.
Plasma
Photomicrograph: Smear of human blood
(1670x); shows two white blood cells
surrounded by red blood cells.
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35. Figure 4.9a Muscle tissues.
Skeletal muscle
Description: Long, cylindrical,
multinucleate cells; obvious
striations.
Part of
muscle
fiber (cell)
Function: Voluntary movement;
locomotion; manipulation of the
environment; facial expression;
voluntary control.
Nuclei
Location: In skeletal muscles
attached to bones or occasionally
to skin.
Striations
Photomicrograph: Skeletal muscle
(approx. 440x). Notice the obvious banding
pattern and the fact that these large cells are
multinucleate.
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36. Figure 4.9b Muscle tissues.
Cardiac muscle
Description: Branching, striated,
generally uninucleate cells that
interdigitate at specialized
junctions (intercalated discs).
Intercalated
discs
Function: As it contracts, it
propels blood into the circulation;
involuntary control.
Striations
Location: The walls of the heart.
Nucleus
Photomicrograph: Cardiac muscle (900x);
notice the striations, branching of cells, and
the intercalated discs.
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37. Figure 4.9c Muscle tissues.
Smooth muscle
Description: Spindle-shaped
cells with central nuclei; no
striations; cells arranged closely
to form sheets.
Function: Propels substances or
objects (foodstuffs, urine, a baby)
along internal passageways;
involuntary control.
Nuclei
Location: Mostly in the walls of
hollow organs.
Smooth
muscle
cell
Photomicrograph: Sheet of smooth
muscle (720x).
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38. Description: Neurons are branching cells; cell processes
Figure Nervous tissue.
Nervous tissue
Description: Neurons are
branching cells; cell processes
that may be quite long extend from
the nucleus-containing cell body;
also contributing to nervous tissue
are nonexcitable supporting cells.
Nuclei of
supporting
cells
Neuron processes
Cell body
Axon Dendrites
Cell body
of a neuron
Function: Neurons transmit
electrical signals from sensory
receptors and to effectors (muscles
and glands) which control their
activity; supporting cells support
and protect neurons.
Neuron
processes
Location: Brain, spinal
cord, and nerves.
Photomicrograph: Neurons (350x).
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39. Figure 4.11 Classes of membranes.
Cutaneous membrane
Serous membranes
The cutaneous membrane
(the skin) covers the body surface.
Serous membranes line body
cavities that are closed to the
exterior.
Cutaneous
membrane (skin)
Parietal
pleura
Visceral
pleura
Mucous membranes
Parietal
pericardium
Visceral
pericardium
Mucous membranes line body
cavities that are open to the
exterior.
Mucosa of
nasal cavity
Mucosa of
mouth
Esophagus
lining
Parietal
peritoneum
Mucosa of
lung bronchi
Visceral
peritoneum
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40. Figure 4.11a Classes of membranes.
Cutaneous membrane
The cutaneous membrane
(the skin) covers the body surface.
Cutaneous
membrane (skin)
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41. Figure 4.11b Classes of membranes.
Mucous membranes
Mucous membranes line body
cavities that are open to the
exterior.
Mucosa of
nasal cavity
Mucosa of
mouth
Esophagus
lining
Mucosa of
lung bronchi
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42. Figure 4.11c Classes of membranes.
Serous membranes
Serous membranes line body cavities that are closed to the exterior.
Parietal
pleura
Visceral
pleura
Parietal
peritoneum
Parietal
pericardium
Visceral
pericardium
Visceral
peritoneum
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43. Area of granulation tissue in growth
Figure Tissue repair of a nonextensive skin wound: regeneration and fibrosis.
Area of granulation tissue in growth
Blood clot in incised wound
Scab
Regenerating epithelium
Regenerated epithelium
Epidermis
Vein
Fibroblast
Macro-phage
Migrating
white
blood cell
Inflammatory
chemicals
Budding capillary
Artery
Fibrosed area 1
Inflammation sets the stage:
• Severed blood vessels bleed.
• Inflammatory chemicals are
released.
• Local blood vessels become
more permeable, allowing white
blood cells, fluid, clotting
proteins, and other plasma
proteins to seep into the injured
area.
• Clotting occurs; surface dries
and forms a scab. 2
Organization restores the blood supply:
• The clot is replaced by granulation
tissue, which restores the vascular
supply.
• Fibroblasts produce collagen fibers
that bridge the gap.
• Macrophages phagocytize dead and
dying cells and other debris.
• Surface epithelial cells multiply and
migrate over the granulation tissue. 3
Regeneration and fibrosis effect permanent repair:
• The fibrosed area matures
and contracts; the epithelium
thickens.
• A fully regenerated epithelium
with an underlying area of
scar tissue results.
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44. Scab Epidermis Vein Blood clot in incised wound Inflammatory chemicals
Figure Tissue repair of a nonextensive skin wound: regeneration and fibrosis. (1 of 3)
Scab
Epidermis
Vein
Blood clot in
incised wound
Inflammatory
chemicals
Migrating white
blood cell
Artery 1
Inflammation sets the stage:
• Severed blood vessels bleed.
• Inflammatory chemicals are released.
• Local blood vessels become more permeable, allowing white blood cells,
fluid, clotting proteins, and other plasma proteins to seep into the injured area.
• Clotting occurs; surface dries and forms a scab.
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45. Organization restores the blood supply:
Figure Tissue repair of a nonextensive skin wound: regeneration and fibrosis. (2 of 3)
Regenerating
epithelium
Area of
granulation
tissue
ingrowth
Fibroblast
Macrophage
Budding capillary 2
Organization restores the blood supply:
• The clot is replaced by granulation tissue, which restores the vascular
supply.
• Fibroblasts produce collagen fibers that
bridge the gap.
• Macrophages phagocytize dead and dying cells and other debris.
• Surface epithelial cells multiply and migrate over the granulation tissue.
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46. Regeneration and fibrosis effect permanent repair:
Figure Tissue repair of a nonextensive skin wound: regeneration and fibrosis. (3 of 3)
Regenerated
epithelium
Fibrosed area 3
Regeneration and fibrosis effect permanent repair:
• The fibrosed area matures and
contracts; the epithelium thickens.
• A fully regenerated epithelium with
an underlying area of scar tissue results.
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47. 16-day-old embryo (dorsal surface view) Muscle and connec-
Figure Embryonic germ layers and the primary tissue types they produce.
16-day-old embryo
(dorsal surface view)
Muscle and connec-
tive tissue (mostly
from mesoderm)
Epithelium
(from all three
germ layers)
Ectoderm
Nervous tissue
(from ectoderm)
Mesoderm
Inner lining of
digestive system
(from endoderm)
Endoderm
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48. Closer Look 4.1
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