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Integument—a fancy word for skin

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1 Integument—a fancy word for skin
Rachel Boggus

2 Skin What are the functions of skin? (4 things)
What is considered part of the skin? (VERY GENERALLY)

3 Skin What are the functions of skin?
Protective barrier Prevents desiccation of the body Temperature regulation Sense organ What is considered part of the skin? (VERY GENERALLY) Epidermis, dermis, and hypodermis (sometimes)

4 Epidermis What type of epithelium? What does it give rise to?
What are the different cell types?

5 Epidermis What type of epithelium? What does it give rise to?
Statified squamous, keratinized What does it give rise to? Accessory organs—hair, nails, sweat glands (eccrine and apocrine) and sebaceous glands What are the different cell types? Keratinocytes—most cells Melanocytes—form pigment Langerhans cells—immune reactions Merkel cells—related to specialized innervation

6 Dermis What does it include? What are the two layers?

7 Dermis What does it include?
Collagen fibers and elastic fibers, GAGs (proteoglycans), fibroblasts, nerve endings, blood vessels, lymphatic vessels, smooth muscle What are the two layers and their features? Papillary layer—loose irregular CT below basement membrane Reticular layer—dense irregular CT

8 Back to the Epidermis What are the 5 layers?
What is the predominant cell type that undergoes differentiation in these layers?

9 Back to the Epidermis What are the 5 layers?
Stratum basale Stratum spinosum Stratum granulosum Stratum lucidum Stratum corneum What is the predominant cell type that undergoes differentiation in these layers? The keratinocyte

10 The changing keratinocytes
What do keratinocytes look like in the stratum basale (both LM and EM)?

11 The changing keratinocytes
What do keratinocytes look like in the stratum basale (both LM and EM)? LM—single basal layer—cells cuboidal columnar and basophilic Sometimes undergoing mitosiskeratinocytes for other strata EM—keratin filaments abundant in the cytoplasm, also have many free ribosomes

12 Nice LM of the stratum basale

13 Stratum Spinosum Describe this layer in the EM and LM?

14 Stratum Spinosum Describe this layer in the EM and LM?
LM—cells become polygonal and flattened, several cells thick with lots of intracellular bridges—where desmosomes are present EM—increase in number of desmosomes with increased cytoplasmic bundles (tonofibrils) Membrane coating granules (MCG) appear in the cytoplasm of keratinocytes in upper layers of stratum spinosum First appear near the golgi Apparatus

15 EM of stratum spinosum

16 LM of stratum spinosum

17 Stratum Granulosum Describe this layer in both the light microscope and electron microscope

18 Stratum Granulosum Describe this layer in both the light microscope and electron microscope LM—large basophilic and irregularly shaped keratohyalin granules numerous EM—KHGs are large, irregularly shaped not bounded by cell membrane, MCGs more numerous, migrate to periphery So have both keratohyalin granules AND MCGs

19 LM stratum granulosum

20 Stratum lucidum Describe its appearance in both EM and LM

21 Stratum lucidum Describe its appearance in both EM and LM
LM—nuclei not evident in flattened cells with pale if any staining EM—organization of keratin filaments more regular

22 Stratum corneum Describe in EM and LM

23 Stratum corneum Describe in EM and LM
LM—cells flattened and scale like, cytoplasm uniform and acidophilic, no nuclei EM—orderly aggregated Keratin filaments Cell envelope—formed in cytoplasm adjacent to plasma membrane Lipids from MCG cross-link to cell enveloperesists fluid penetration

24 LM of Stratum lucidum and stratum corneum

25 Melanocytes Where do they originate from?
How do they deliver melanosomes? What is the process called? What are melanosomes?

26 Melanocytes Where do they originate from?
Neural crest cells How do they deliver melanosomes? What is the process called? Via dendritic processes extending between keratinocytescytocrine transfer What are melanosomes? Vesicles in which melanin is formed

27 More on melanosomes They contain the enzyme tyrosinase which takes tyrosineDOPAdopaquinone What happens in dark skin vs. light skin?

28 More on melanosomes They contain the enzyme tyrosinase which takes tyrosineDOPAdopaquinone What happens in dark skin vs. light skin? In dark skin melanosomes remain as single structures retained by keratinocytes In light skin—melanosomes aggregate and are degraded by hydrolytic enzymes from lysosomes in stratum spinosum

29 EM of melanosomes (labled 5)

30 Langerhans Cells Macrophage of the skin
Most frequent in the stratum spinosum

31 Merkel cells Found in stratum basale Maybe mechanoreceptors
Many dense core granules may contain neurotransmitters

32 Do you have thick skin? What is different about thick skin vs. thin skin?

33 Do you have thick skin? What is different about thick skin vs. thin skin? Thick skin lacks hair follicles and sebaceous glands Two layers of skin are bound to each other by epidermal ridges—rete pegs and dermal papillae

34

35 Dermis Describe the papillary layer? Describe the reticular layer?

36 Dermis Describe the papillary layer? Describe the reticular layer?
Just below epidermis and includes dermal papillae. Loose irregular ct and includes collagen, elastic fibers, GAGs, fibroblasts, etc Describe the reticular layer? Dense irregular ct (thicker than papillary layer) collagen, and other ct constituents

37

38 Blood vessels of the dermis
Found in 2-3 plexuses Subpapillary plexus—at the junction of the papillary and reticular layerscapillaries in papillary layer Cutaneous plexus—at junction of reticular layer and hypodermis Third plexus below hypodermis

39 Nerve endings What are the different types?

40 Nerve endings What are the different types and what are they for?
Pacinian corpuscles—deep pressure Meissner’s corpuscles—light touch Free nerve endings—pain, fine touch, heat and cold receptors Ruffini corpuscles—in collagen fibers, respond when fibers are mechanically stressed/displaced

41 Pacinian corpuscle – green arrow
For the gunners: whats the blue arrow?

42 COWS Circle Of Wavy Shit
Peripheral nerve – this one is cut in cross section

43 Meisner’s Corpuscles - green

44 Accessory Organs Hair– what is vellus hair vs. terminal hair
What are follicles?

45 Accessory Organs Hair– what is vellus hair vs. terminal hair
Vellus hairpeach fuzz Terminal hairthicker hair, formed from vellus hair What are follicles? Invagination of epidermal cells into the dermis Formation induced by protrusion of dermis, dermal papilla into the hair bulb

46 More hair crap What are the epidermal cells adjacent to the dermal papilla called? What are they?

47 More hair crap What are the epidermal cells adjacent to the dermal papilla called? Matrix cells What are they? Proliferative cells that correspond to the stratum basale They give rise to different layers of the hair shaft—medulla, cortex and cuticle

48 What layers of the epidermis can be seen where on the hair?

49 What layers of the epidermis can be seen where?
Upper 1/3—all layers of the epidermis are evident Middle 1/3—only lower two layers of epidermis Lower 1/3—limited only to basal layer—continuous with the hair bulb

50 I thought we needed a picture
Don’t worry, there will be plenty more later on

51 What happens to matrix keratinocytes?
When they proliferate they form hard keratin Matrix cells peripheral to the cells forming the hair shaft form the internal root sheath that surrounds the hair shaft within the follicle.

52 Hair crap just goes on and on…
What are epidermal cells that form the hair follicle called? And the dermis surrounding the hair follicle is called? What about the basement membrane?

53 Hair crap just goes on and on…
What are epidermal cells that form the hair follicle called? External root sheath And the dermis surrounding the hair follicle is called? Connective tissue root sheath What about the basement membrane? Glassy membrane… its really thick Between external root sheath and connective tissue sheath

54 ALMOST FINISHED WITH HAIR
What is the arrector pili muscle?

55 ALMOST FINISHED WITH HAIR
What is the arector pili muscle? Bundle of smooth muscle attached to connective tissue of the follicle and the basement membrane of epidermis Contraction in response to cold or fear makes the hair erect

56 Phases of hair growth And of course they couldn’t just call the phases of hair growth growing, receding, and resting because that would make sense. Instead, its anagen, catagen, and telogen At the end of anagen(growing) the catagen (receding) phase begins with follicle receding toward epidermal surface, dermal papilla lost During telogen—hair shaft is released Then the next anagen phase begins as new papilla formed and new hair shaft arises

57 See papilla so it must be anagen

58 Sebaceous glands Simple, branched acinar glands
Derived from outpouching of basal cells in upper 1/3 of hair follicle Glands secrete by HOLOCRINE mode of secretion Lack myoepithelial cells Become active during puberty Acne is caused by obstruction of these glands

59 Sebaceous glands galore

60 Sweat glands Eccrine (merocrine) sweat gland
Simple, coiled, tubular glands Numerous, assoc. with skin all over the body Two types of secretory cells?

61 Sweat glands Eccrine (merocrine) sweat gland
Simple, coiled, tubular glands Numerous, assoc. with skin all over the body Two types of secretory cells? Light (clear) cells—more numerous than Mucous (dark) cells—responsible for secretory product

62 Sweat What does sweat consist of?

63 Sweat What does sweat consist of? Water and sodium chloride
Secretion from light cells released from apical surface of cells and into intercellular canaliculi Between the base of the secretory cells and the basal lamina are myoepithelial cells—resemble smooth muscle Ducts of glands extend to epidermal surface lined by stratified cuboidal epi. Duct cells active in reabsorption of NaCl ions from secretory product Reabsorption regulated by aldosterone

64 Duct Secretory portion

65 Apocrine sweat gland Simple branched coiled tubular glands
Where are they located? How are they different from eccrine glands?

66 Apocrine sweat gland Simple branched coiled tubular glands
Where are they located? Axilla, pubic, areola, and circumanal regions Note: I have a funny story to tell here, don’t let me forget How are they different from eccrine glands? Larger lumens, only one type of secretory cell present Acidic secretory granules often visable

67 DUCT SECRETORY PORTION

68 Nail Composed of nail plate with root and free edge
Nail consists of scales of cornified cells What is the eponychium? Hyponychium?

69 Nail Composed of nail plate with root and free edge
Nail consists of scales of cornified cells What is the eponychium? Region where nail emerges from epidermis at the junction with the stratum corneum Hyponychium? Where nail leaves nail bed to form free edge

70 Nail the nail

71 Image review Get ready….

72 Layers of skin – what you need to know
Epidermis (basale, spinosum, granulosum, lucidum, corneum) Dermis (papillary layer, reticular layer) Basically just CT Hypodermis Contains a lot of adipose

73 Sweat glands Apocrine and eccrine Secretory portion Duct
Myoepithelial cells Eccrine have flat-topped epithelium and are found EVERYWHERE SIMPLE coiled tubular Apocrine have rounded/rough looking tops and are found in your pits and private areas BRANCHED coiled tubular

74 Hair follicles Associated with smooth muscle of arrector pili muscles
Also associated with sebaceous glands that DO NOT have myoepithelial cells

75 A little embryo action Keratinocytes (corneum, lucidum, etc. etc.), hair follicles, sweat glands, sebaceous glands from ECTODERM Epidermal stuff Fibroblasts, smooth muscle cells, macrophages from MESODERM Dermal stuff

76 Thick skin – a ton of corneum; soles of feet and palms

77 Close up Pap. layer Retic. layer

78 More thick skin The elusive lucidum

79 corneum lucidum granulosum spinosum basale

80 lucidum granulosum spinosum basale

81 Epidermal pegs/rete pegs (white) – epidermis that bulges into dermis; anchor epidermis to dermis; dermal papillae (blue) is the dermis that bulges into epidermis. Got it?

82 dermis Papillary layer on top Reticular layer on the bottom Looser CT
Contains blood vessels, nerve endings (esp. in dermal papilla) Reticular layer on the bottom Denser CT (dense irregular CT)

83 Thin skin – only a few corneum layers
Another clue = see hair and oil glands

84 Now time for its close up of thin skin; notice the brown melanin pigment

85 Hair follicle – must be thin skin

86 Cross section hair follicle and oil gland

87 Sebaceous glands – NOT in thick skin

88 So much shit Oil gland Sweat gland Thin skin Reticular layer of dermis
Adipose in hypodermis

89 Blue = smooth muscle of arrector pili, note that’s its near a sebaceous gland

90 Apocrine sweat glands – rough tops

91 Remember the meissners corpuscle for touch in the dermal papillae???

92 Pacinian corpuscle in the dermis-hypodermis junction – onion rings

93

94

95

96 Thick skin showing epithelial detail
Thick skin showing epithelial detail. Cornified (keratinized) stratified squamous epithelium makes up the epidermis. The stratum granulosum is very dark; the stratum lucidum is bright red. The stratum corneum is thick, and very pale.

97 Detail of epithelium of thick skin from the superficial to deep:
pale stratum corneum bright red stratum lucidum purple stratum granulosum stratum spinosum

98 THIS WAS ON OUR EXAM Many desmosomes between cells (arrows). The cell membranes of the two cells are repeatedly interdigitated, giving the appearance of "intercellular bridges" in light microscopy. These bundles of keratin filaments are called TONOFIBRILS.

99 Detail of epithelium of thin skin, showing melanin in the basal layer
Detail of epithelium of thin skin, showing melanin in the basal layer. The pigment is produced by stellate shaped melanocytes of the dermal layer and then deposited in the basal cells of the epidermis. Melanocytes are of neural crest origin and have to be specifically stained in order to be seen.

100 Thick skin – check out the corneum

101

102 Papillary (finer strands) vs
Papillary (finer strands) vs. reticular (thicker collagen strands) dermis

103 Meissners corpuscle in dermal papilla: This is a touch receptor

104 Meissner’s

105 The secretory portions of several sweat glands lie in clusters among the fat cells of the hypodermis, low in the picture. A Pacinian corpuscle is in the same area. These are the eccrine sweat glands of skin – they secrete their watery fluid by merocrine secretion. pacinian Eccrine sweat

106 Notice that the last slide was thick skin
Notice that the last slide was thick skin. It DOES have sweat glands, just no hair follicles or oil glands. Think about it. Does anyone you know have hairy feet? I hope not. Also, makes sense why the lotion business is huge – no oil glands on hands!

107 Eccrine sweat glands and ducts

108 Detail of sweat gland. The darker circles in the lower part of the field are ducts; the lighter cross-cuts above are the secretory portions.

109 Eccrine sweat gland

110 The ducts are distinguished by their stratified cuboidal appearance and the fact that they are much denser

111 eccrine

112 eccrine

113 Apocrine – ruffled tops… where are these found??? ;)

114 apocrine                                                          

115 Apocrine!

116 Apocrine sebaceous

117

118

119

120

121

122

123 (1) hair shaft; (2) connective tissue sheath; (3) external root sheath; (4) internal root sheath; (5) dermal papilla; (6) germinal matrix

124

125 Hair follicles of scalp, with associated pale sebaceous glands
Hair follicles of scalp, with associated pale sebaceous glands. The follicles extend down into the hypodermis, which is largely adipose tissue. Notice the arrector pili (orange) muscle running diagonally toward the upper right-hand corner of the field.

126 At the base of a hair follicle sebaceous glands (red) are found
At the base of a hair follicle sebaceous glands (red) are found. These glands secrete oil into the follicle. They secrete via a process called "holocrine secretion" in which the cell fills with secretory material and then essentially distintegrates; the whole cell is shed

127 Detail of sebaceous gland
Detail of sebaceous gland. Cells look foamy because of loss of lipid droplets during tissue fixation. This gland exhibits holocrine secretion, in which whole cells swell up, degenerate, and are desquamated. The secretion is emptied into the hair follicles and eventually reaches the surface of the skin.

128

129 Identify the layer identified by the arrow

130 Hints: You are in the epidermis Answer: Stratum spinosum You know because you could see the intracellular bridges

131 Identify

132 Hints: This is cut in cross section!
Answer: It’s a hair follicle

133 Identify

134 Hints: Answer: It’s a pacinian corpuscle
You know because of its onion-like appearance

135 Identify

136 Answer: Arrector Pili muscle
Hints: What can you see on the slide? What type of tissue is it? Answer: Arrector Pili muscle

137 Identify

138 Is it associated with a hair follicle?
Hints What type of tissue? Is it associated with a hair follicle? Answer: Eccrine gland

139 What is indicated by each arrow?

140 Hints Answer: What is the main structure in the image?
Blue arrow—vascular pole Green arrow—urinary pole

141 Identify

142 Hints: C-shaped cartilage Answer: trachea

143 Identify

144 Hints epithelium Presence of glands Answer: False vocal fold/cord

145 Identify

146 Hints What type of tissue? Is it associated with hair? Answer:
Sebaceous gland What mode of secretion? Holocrine

147 Identify blue arrow

148 Hints: Where are you? Answer: Rete pegs/epidermal ridges

149 Identify

150 Hints: Layer of epidermis Answer: Stratum basale

151 1? 2?

152 (1) arrector pili muscle; (2) sebaceous gland

153 What is at the white arrow and what layer(s) of the skin are shown in this image?

154 sweat gland (secretory unit and duct) in the hypodermis

155 What type of skin is this?

156 THIN!!!!!!! – you can see a snip of arrector pili at the bottom as a clue!

157 Identify the multicellular structure at the tip of each of the numbered arrows.

158 (1) Meissner's corpuscle; (2) dermal papilla

159 What is the brown material at the tips of the arrows?

160 MELANIN

161 WHEW!!!!


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