Integumenta fancy word for skinRachel BoggusBoggusrl@email.uc.edu

SkinWhat are the functions of skin? (4 things)

What is considered part of the skin? (VERY GENERALLY)

SkinWhat are the functions of skin?Protective barrierPrevents desiccation of the bodyTemperature regulationSense organWhat is considered part of the skin? (VERY GENERALLY)Epidermis, dermis, and hypodermis (sometimes)

EpidermisWhat type of epithelium?

What does it give rise to?

What are the different cell types?

EpidermisWhat type of epithelium?Statified squamous, keratinizedWhat does it give rise to?Accessory organshair, nails, sweat glands (eccrine and apocrine) and sebaceous glandsWhat are the different cell types?Keratinocytesmost cells Melanocytesform pigmentLangerhans cellsimmune reactionsMerkel cellsrelated to specialized innervation

DermisWhat does it include?

What are the two layers?

DermisWhat does it include?Collagen fibers and elastic fibers, GAGs (proteoglycans), fibroblasts, nerve endings, blood vessels, lymphatic vessels, smooth muscleWhat are the two layers and their features?Papillary layerloose irregular CT below basement membraneReticular layerdense irregular CT

Back to the EpidermisWhat are the 5 layers?

What is the predominant cell type that undergoes differentiation in these layers?

Back to the EpidermisWhat are the 5 layers?Stratum basaleStratum spinosumStratum granulosumStratum lucidumStratum corneumWhat is the predominant cell type that undergoes differentiation in these layers?The keratinocyte

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

The changing keratinocytesWhat do keratinocytes look like in the stratum basale (both LM and EM)?LMsingle basal layercells cuboidal columnar and basophilicSometimes undergoing mitosiskeratinocytes for other strataEMkeratin filaments abundant in the cytoplasm, also have many free ribosomes

Nice LM of the stratum basale

Stratum SpinosumDescribe this layer in the EM and LM?

Stratum SpinosumDescribe this layer in the EM and LM?LMcells become polygonal and flattened, several cells thick with lots of intracellular bridgeswhere desmosomes are presentEMincrease in number of desmosomes with increased cytoplasmic bundles (tonofibrils)Membrane coating granules (MCG) appear in the cytoplasm of keratinocytes in upper layers of stratum spinosumFirst appear near the golgi Apparatus

EM of stratum spinosum

LM of stratum spinosum

Stratum GranulosumDescribe this layer in both the light microscope and electron microscope

Stratum GranulosumDescribe this layer in both the light microscope and electron microscopeLMlarge basophilic and irregularly shaped keratohyalin granules numerousEMKHGs are large, irregularly shaped not bounded by cell membrane, MCGs more numerous, migrate to peripherySo have both keratohyalin granules AND MCGs

LM stratum granulosum

Stratum lucidumDescribe its appearance in both EM and LM

Stratum lucidumDescribe its appearance in both EM and LMLMnuclei not evident in flattened cells with pale if any stainingEMorganization of keratin filaments more regular

Stratum corneumDescribe in EM and LM

Stratum corneumDescribe in EM and LMLMcells flattened and scale like, cytoplasm uniform and acidophilic, no nucleiEMorderly aggregated Keratin filamentsCell envelopeformed in cytoplasm adjacent to plasma membraneLipids from MCG cross-link to cell enveloperesists fluid penetration

LM of Stratum lucidum and stratum corneum

MelanocytesWhere do they originate from?

How do they deliver melanosomes? What is the process called?

What are melanosomes?

MelanocytesWhere do they originate from?Neural crest cellsHow do they deliver melanosomes? What is the process called?Via dendritic processes extending between keratinocytescytocrine transferWhat are melanosomes?Vesicles in which melanin is formed

More on melanosomesThey contain the enzyme tyrosinase which takes tyrosineDOPAdopaquinoneWhat happens in dark skin vs. light skin?

More on melanosomesThey contain the enzyme tyrosinase which takes tyrosineDOPAdopaquinoneWhat happens in dark skin vs. light skin?In dark skin melanosomes remain as single structures retained by keratinocytesIn light skinmelanosomes aggregate and are degraded by hydrolytic enzymes from lysosomes in stratum spinosum

EM of melanosomes (labled 5)

Langerhans CellsMacrophage of the skinMost frequent in the stratum spinosum

Merkel cellsFound in stratum basaleMaybe mechanoreceptorsMany dense core granules may contain neurotransmitters

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

Do you have thick skin?What is different about thick skin vs. thin skin?Thick skin lacks hair follicles and sebaceous glandsTwo layers of skin are bound to each other by epidermal ridgesrete pegs and dermal papillae

DermisDescribe the papillary layer?

Describe the reticular layer?

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

Blood vessels of the dermisFound in 2-3 plexusesSubpapillary plexusat the junction of the papillary and reticular layerscapillaries in papillary layerCutaneous plexusat junction of reticular layer and hypodermisThird plexus below hypodermis

Nerve endingsWhat are the different types?

Nerve endingsWhat are the different types and what are they for? Pacinian corpusclesdeep pressureMeissners corpuscleslight touchFree nerve endingspain, fine touch, heat and cold receptorsRuffini corpusclesin collagen fibers, respond when fibers are mechanically stressed/displaced

Pacinian corpuscle green arrowFor the gunners: whats the blue arrow?

COWSCircle OfWavyShit

Peripheral nerve this one is cut in cross section

Meisners Corpuscles - green

Accessory OrgansHair what is vellus hair vs. terminal hair

What are follicles?

Accessory OrgansHair what is vellus hair vs. terminal hairVellus hairpeach fuzzTerminal hairthicker hair, formed from vellus hairWhat are follicles?Invagination of epidermal cells into the dermisFormation induced by protrusion of dermis, dermal papilla into the hair bulb

More hair crapWhat are the epidermal cells adjacent to the dermal papilla called?

What are they?

More hair crapWhat are the epidermal cells adjacent to the dermal papilla called?Matrix cellsWhat are they?Proliferative cells that correspond to the stratum basaleThey give rise to different layers of the hair shaftmedulla, cortex and cuticle

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

What layers of the epidermis can be seen where?Upper 1/3all layers of the epidermis are evidentMiddle 1/3only lower two layers of epidermisLower 1/3limited only to basal layercontinuous with the hair bulb

I thought we needed a pictureDont worry, there will be plenty more later on

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

Hair crap just goes on and onWhat are epidermal cells that form the hair follicle called?

And the dermis surrounding the hair follicle is called?

What about the basement membrane?

Hair crap just goes on and onWhat are epidermal cells that form the hair follicle called?External root sheathAnd the dermis surrounding the hair follicle is called?Connective tissue root sheathWhat about the basement membrane?Glassy membrane its really thickBetween external root sheath and connective tissue sheath

ALMOST FINISHED WITH HAIR What is the arrector pili muscle?

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

Phases of hair growthAnd of course they couldnt just call the phases of hair growth growing, receding, and resting because that would make sense.Instead, its anagen, catagen, and telogenAt the end of anagen(growing) the catagen (receding) phase begins with follicle receding toward epidermal surface, dermal papilla lostDuring telogenhair shaft is releasedThen the next anagen phase begins as new papilla formed and new hair shaft arises

See papilla so it must be anagen

Sebaceous glandsSimple, branched acinar glandsDerived from outpouching of basal cells in upper 1/3 of hair follicleGlands secrete by HOLOCRINE mode of secretionLack myoepithelial cellsBecome active during pubertyAcne is caused by obstruction of these glands

Sebaceous glands galore

Sweat glandsEccrine (merocrine) sweat glandSimple, coiled, tubular glandsNumerous, assoc. with skin all over the bodyTwo types of secretory cells?

Sweat glandsEccrine (merocrine) sweat glandSimple, coiled, tubular glandsNumerous, assoc. with skin all over the bodyTwo types of secretory cells?Light (clear) cellsmore numerous thanMucous (dark) cellsresponsible for secretory product

SweatWhat does sweat consist of?

SweatWhat does sweat consist of?Water and sodium chlorideSecretion 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 cellsresemble smooth muscleDucts of glands extend to epidermal surface lined by stratified cuboidal epi.Duct cells active in reabsorption of NaCl ions from secretory productReabsorption regulated by aldosterone

DuctSecretory portion

Apocrine sweat glandSimple branched coiled tubular glandsWhere are they located?

How are they different from eccrine glands?

Apocrine sweat glandSimple branched coiled tubular glandsWhere are they located?Axilla, pubic, areola, and circumanal regionsNote: I have a funny story to tell here, dont let me forgetHow are they different from eccrine glands?Larger lumens, only one type of secretory cell presentAcidic secretory granules often visable

DUCTSECRETORY PORTION

NailComposed of nail plate with root and free edgeNail consists of scales of cornified cellsWhat is the eponychium?Hyponychium?

NailComposed of nail plate with root and free edgeNail consists of scales of cornified cellsWhat is the eponychium?Region where nail emerges from epidermis at the junction with the stratum corneumHyponychium?Where nail leaves nail bed to form free edge

Nail the nail

Image reviewGet ready.

Layers of skin what you need to knowEpidermis (basale, spinosum, granulosum, lucidum, corneum)Dermis (papillary layer, reticular layer)Basically just CTHypodermisContains a lot of adipose

Sweat glandsApocrine and eccrineSecretory portionDuctMyoepithelial cells

Eccrine have flat-topped epithelium and are found EVERYWHERESIMPLE coiled tubularApocrine have rounded/rough looking tops and are found in your pits and private areasBRANCHED coiled tubular

Hair folliclesAssociated with smooth muscle of arrector pili musclesAlso associated with sebaceous glands that DO NOT have myoepithelial cells

A little embryo actionKeratinocytes (corneum, lucidum, etc. etc.), hair follicles, sweat glands, sebaceous glands from ECTODERMEpidermal stuffFibroblasts, smooth muscle cells, macrophages from MESODERMDermal stuff

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

Close up Pap. layerRetic. layer

More thick skinThe elusive lucidum

lucidumgranulosumspinosumbasalecorneum

lucidumgranulosumspinosumbasale

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?

dermisPapillary layer on topLooser CTContains blood vessels, nerve endings (esp. in dermal papilla)Reticular layer on the bottomDenser CT (dense irregular CT)

Thin skin only a few corneum layers

Another clue = see hair and oil glands

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

Hair follicle must be thin skin

Cross section hair follicle and oil gland

Sebaceous glands NOT in thick skin

So much shitAdipose in hypodermisThin skinReticular layer of dermisOil glandSweat gland

Blue = smooth muscle of arrector pili, note thats its near a sebaceous gland

Apocrine sweat glands rough tops

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

Pacinian corpuscle in the dermis-hypodermis junction onion ringsDERMISHYPODERMIS

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.

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

THIS WAS ON OUR EXAMMany 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.

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.

Thick skin check out the corneum

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

Meissners corpuscle in dermal papilla: This is a touch receptor

Meissners

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. pacinianEccrine sweat

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!

Eccrine sweat glands and ducts

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.

Eccrine sweat gland

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

eccrine

eccrine

Apocrine ruffled tops where are these found??? ;)

apocrine

Apocrine!

Apocrine sebaceous

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

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.

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

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.

Identify the layer identified by the arrow

Hints:

You are in the epidermisAnswer: Stratum spinosumYou know because you could see the intracellular bridges

Identify

Hints: This is cut in cross section!

Answer:Its a hair follicle

Identify

Hints:

Answer:Its a pacinian corpuscleYou know because of its onion-like appearance

Identify

Hints:What can you see on the slide?What type of tissue is it?

Answer: Arrector Pili muscle

Identify

HintsWhat type of tissue?Is it associated with a hair follicle?

Answer:Eccrine gland

What is indicated by each arrow?

HintsWhat is the main structure in the image?

Answer:Blue arrowvascular poleGreen arrowurinary pole

Identify

Hints:C-shaped cartilage

Answer:trachea

Identify

Hintsepithelium Presence of glands

Answer:False vocal fold/cord

Identify

HintsWhat type of tissue?Is it associated with hair?

Answer:Sebaceous gland

What mode of secretion?Holocrine

Identify blue arrow

Hints:Where are you?

Answer:Rete pegs/epidermal ridges

Identify

Hints:Layer of epidermis

Answer:Stratum basale

1? 2?

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

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

sweat gland (secretory unit and duct) in the hypodermis

What type of skin is this?

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

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

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

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

MELANIN

WHEW!!!!