09.24.08: Skin and Glands

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CellsandTissuesSequenceMedicalHistology

IntegumentarySystem,Glands/mammarygland

Fall,2008

CellandDevelopmentalBiology

TheIntegument

1.Skin: EpidermisandDermisHypodermis(a.k.a.superficialfascia)2.Appendages:SpecializationofepidermisA.Pilosebaceousapparatus

HairSebaceousglandsArrectopilimuscle

B.Sweatglands EccrinesweatglandsApocrine(odoriferous)sweatglands

C.  Nail

“Mammarygland”

Theskinconsistsofepidermisanddermis

andisthelargestorganinthebody,

accountingforabout16%ofthebodyweight.

UMMedicalSchoolAnatomyLaboratoryManual

Functionsofskin

1.Protection(fromabrasion,friction,infection,UVrays)Keratin,melanin

2.PermeabilityBarrier(preventionofextremewaterloss)Keratin,lipid,sebum

3.ThermoregulationSweatglands,bloodvessels,fat

4.SensoryPerceptionFreeandencapsulatednerveendings

5.ImmunologicDefenseKeratinocytes,Langerhanscells

6.Dermatoglyphics(fingerprints)

SkinEpidermis:Keratinized,strat.sq.epithelium

Dermis:Denseirregularct.TypeIIIandTypeIcollagenElasticfibers

SweatGlands:EccrineandApocrineglands

Hypodermis(superficialfascia):Fattyconn.Tissue

MichiganMedicalSchoolHistologySlideCollection

CellsoftheEpidermis

Keratinocytes(80%)Melanocytes(5-10%)Langerhanscells(5%)Merkelcells(<1%)

MichiganMedicalSchoolHistologySlideCollection

CellularLayersoftheEpidermis

Dermis

Epidermis Epidermis

DermisMichiganMedicalSchoolHistologySlideCollection Weiss,L.,CellandTissueBiology6thed.P.543

CellsoftheStratumBasaleSt.Spinosum

St.Basale

Dermis

Source Undetermined

Stratumspinosum

Source Undetermined

BlisteringSkinDisorders

Pemphigus:Separationofepidermalcellsfromeachother(acantholysis)causedbylossofdesmosomefunctions.

Bullouspemphigoid:Separationofepidermisfromthedermisduetoblisteringinthebasementmembranecausedbylossofanchoringfilamentsandhemidesmosomes.

Source Undetermined

StratumGranulosumKeratohyalinGranules(KG) Histidine-richprotein(filaggrin:filamentaggregating

proteinthatcross-linkskeratin) PolysaccharidesandlipidsMembrane-coatinggranules(MCG) (a.k.a.lamellargranules,Odlandbodies) Primaryintercellularlipidbarriertowater-ceramidecross-linkscellmembranes.

KeratohyalinGranules

Weiss,L.,CellandTissueBiology6thed.P.549

MembraneCoatingGranulesPrimaryintercellularbarriertowater

Weiss,CellandTissueBilogy6thed.P.547

Stratumcorneum

15-20layersofnon-nucleatedflattenedcellsfilledwithkeratainfilaments.

Keratinfilamentsarecross-linkedwithfilaggrin.

Thekeratin-filaggrindepositedontheinsideoftheplasmamembraneformathickenedcellenvelope.

Source Undetermined

Thickandthinskin

Bluearrows:CellsofthestratumgranulosumSource Undetermined

Melanocytes

SkincolorRedbloodcellsinthedermalvascularbeds.Carotenesfromexogenousfoodsstoredinfattytissues.Hemoglobinandbilirubin(endogenousdegradationproducts).Melanin(pigmentproducedbymelanocytes)

Melanocytes(neuralcrestorigin)

MichiganMedicalSchoolHistologySlideCollection Rhodin,Histology,pp.485

MelanocytesproduceMelanin

Melanin: Eumelanin Pheomelanin Tyrosinase(deficiency:albinism)Tyrosine 3,4-dihydroxyphenyalanine(dopa) dopaquinone Melanin

Epidermal-

melaninunit

Cytocrinesecretion

Source Undetermined

Ross/Romrell,Histology2nded.P.356

Pigmentdistributioninlight(left)anddark(right)skin

MichiganMedicalSchoolHistologySlideCollection MichiganMedicalSchoolHistologySlideCollection

Merkel’scell Langerhanscell

Bonemarrowderived

Bind,processandpresentantigentoT-lymphocytes

Roleinimmunologicskinreactions.

Fawcett,Histology,pp.536

ProliferationandMaturationofEpithelialCells

Source Undetermined

Psoriasis

Source Undetermined

Dermis

PapillaryDermisReticularDermis

Containsbloodandlymphaticvessels,nerves,hairfollicles,sebaceousglands,arrectopilimuscle,andsweat(eccrineandapocrine)glands

Hypodermis(superficialfasciawithfatcells)

EpithelialPegsandDermalPapillae

Source Undetermined Source Undetermined

Papillary(PL)andReticular(RL)Dermis

TypeIIICollagen

TypeICollagen

Elasticfibers(EF)

Source Undetermined

PapillaryDermishousesbloodvessels,nerveendings,etc.

Epidermis

Papillarydermis

Reticulardermis

MichiganMedicalSchoolHistologySlideCollection SourceUndetermined

Dermisandskincirculation WheaterFig.9.18

Wheater 9.18

Pilosebaceousapparatus

hair,sebaceousglandandarrectopilemuscle

hair

Sebaceousgland

Arrectopilemuscle

Swaetgland

MichiganMedicalSchoolHistologySlideCollection

MichiganMedicalSchoolHistologySlideCollection

(A)

(D)

(B,C)

Hairfollicle:hairbulbandhairshaft

Ross/Romrell,Histology2nded.P.361

Young/HeathWheater’sHistology4thed.P.167

SourceUndetermined

GrowthCycleoftheHairFollicle

testosterone

5αdihydrotestosterone,

whichbindstheintracellularreceptorsandInhibitsthemetabolismofcondemnedfollicles.

5α-reductase(?)

Weiss, pg. 562

Pilo-sebaceousApparatus

Source Undetermined

HolocrineSecretionSource Undetermined

ModeofSecretionMerocrine(Exocytosis)Almostallexocrineglands,includingeccrineandapocrinesweatglands.

Apocrine(somepartsofcellsaresecreted)Mammaryglands(lipidsecretion)

Holocrine(wholecellsaresecreted)Sebaceousglands

Source Undetermined

Hairfollicleandit’sassociatedstructures

Tsaitgaist,,Wikipedia

EccrineSweatGlands

MichiganMedicalSchoolHistologySlideCollection

EccrineSweatGland

Secretoryportion

Secretoryportion

Ducts

Myoepithelialcells

MichiganMedicalSchoolHistologySlideCollection

MyoepithelialCells

Source Undetermined

ApocrineSweatGlands

MichiganMedicalSchoolHistologySlideCollection

ApocrineSweatGlands

Myoepithelialcells

MichiganMedicalSchoolHistologySlideCollection

SecretoryPortionsofEccrineandApocrineSweatGlands

MichiganMedicalSchoolHistologySlideCollection

Source Undetermined

GlandularLobulesandLobesManyLobulesformaLobe.

Source Undetermined

Adapted and modified from Leson TS, Leson CR, Paparo AA: Text/Atlas of Histology. Philadelphia, WB Saunders, 1988

US Federal Government Gray’s Anatomy, Wikimedia Commons

ChangeinMammaryGlandAlveoliandDucts

Inactive:Noalveoliandundifferentiatedterminalducts.

Active(duringpregnancy):Proliferationanddifferentiationofalveoli.

Active(lactating):Secretionofmilkandaccumulationinalveolarlumen.

Source Undetermined

Inactivegland(left):Lobulesarearrangedsparselyandeachlobuleconsistsofmainlybluntlyendingductswithnosecretoryalveoli.Activegland(right):Lobulesarewelldevelopedandpackthegland.Ineachlobule,secretoryalveolihaveformedandtheirlumensarehighlydilated.

Inactiveandactivemammaryglands

MichiganMedicalSchoolHistologySlideCollection(allimages)

Thestromaofthemammarygland

Lactiferousduct

Lobule

Theloose,morecellularandlessfibrous,intralobularconnectivetissuemakesthestromadistensibleforthehypertrophyoftheepithelialelementsanddifferentiationofthealveoli.Numerousplasmacells(arrowsabove),whichappearintheintralobularconnectivetissueduringpregnancyandlactation,produceimmunoglobulinIgA.IgAistakenupbytheepithelialcells,secretedinthemilk,andtransportedtotheinfant’sintestinewheretheantibodiesresistbacterialinfection.

IntralobularCT

InterlobularCT

Source Undetermined

MichiganMedicalSchoolHistologySlideCollection

Theantibodiesresistentericinfections.

Image of mother breastfeeding

infant antibodies removed

Source Undetermined

Nipple-Lactiferousducts15-20independentlactiferousducts,eachdrainingoneofthelobesofthegland,openatthetipofthenipple.Withinthenipple,eachductisslightlydilatedtoformalactiferoussinus(inset).Lactiferousducts

Gray’s Anatomy, Wikimedia Commons

MichiganMedicalSchoolHistologySlideCollection

#265(nipple)Lactiferousducts

Thelactiferousductislinedbyasuperficiallayerofcuboidalepithelialcellsandabasallayerofmyoepithelialcells(arrows).

MichiganMedicalSchoolHistologySlideCollection

LearningObjectives

•  Beabletoidentifyprincipallayersoftheskin(epidermis,dermisandhypodermis)atthelightmicroscopelevelandknowthemajorfunctionsofeachlayer.

•  Beabletoidentifythestrataoftheepidermisinthickandthinskinandknowthemajorcellulareventsthattakeplaceineachlayerintheprocessofkeratinization.

•  Beabletoidentifythecellsindifferentlayeroftheepidermisattheelectronmicroscopelevelbyrecognizingcharacteristicorganellesandstructurespresentineachlayer.

•  Beabletorecognizemelanocytesandknowtheprocessofpigmentformationintheskin.

•  Beabletoidentifyeccrineandapocrinesweatglandsatthelightmicroscopelevelanddistinguishductalandsecretoryportions.

•  Beabletoidentifythecomponentsofthepilosebacousapparatusandknowthestructuralrelationshipbetweeneachcomponentandtheepidermis.

•  Beabletoidentifythemammarygland,byrecognizingitsstructuralcomponents(lactiferousducts,alveoli,lobules,thestromalconnectivetissue),andknowthehistologicaldifferencesinactiveandinactiveglands.

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Slide 5: UM Medical School Anatomy Laboratory Manual Slide 7: Michigan Medical School Histology Slide Collection

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Slide 31: Wheater 9.18

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Slide 34: Weiss, pg. 562 Slide 35: Source Undetermined

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Slide 38: Tsaitgaist, Wikipeda, http://en.wikipedia.org/wiki/File:Hair_follicle-en.svg

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Slide 46: Adapted and modified from Leson TS, Leson CR, Paparo AA: Text/Atlas of Histology. Philadelphia, WB Saunders, 1988; Source Undetermined Slide 47: Gray’s Anatomy, Wikimedia Commons, http://commons.wikimedia.org/wiki/File:Dissected_lactating_breast_gray1172.png;

U.S. Federal Government

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Slide 52: Gray’s Anatomy, Wikimedia Commons, http://commons.wikimedia.org/wiki/File:Dissected_lactating_breast_gray1172.png;

Michigan Medical School Histology Slide Collection

Slide 53: Michigan Medical School Histology Slide Collection