Epithelial Tissue2

8/3/2019 Epithelial Tissue2

1/47

HISTOLOGYHISTOLOGY

Histology is the study of tissues.Histology is the study of tissues.

Tissues are groupings of similar cellsTissues are groupings of similar cellswith a common or related function.with a common or related function.

Tissue types.Tissue types. 1. Epithelial tissues1. Epithelial tissues covering.covering.

2. Connective tissues2. Connective tissues support andsupport and

defense.defense. 3. Nervous tissues3. Nervous tissues -- controlcontrol

4. Muscle tissues4. Muscle tissues movement.movement.


2/47

Tissue Cells ExtracellularMatrix

MainFunctions

Nervous Intertwiningelongated

processes

none Transmission

Epithelial Aggregatedpolyhedral cells

Very scant Liningsurfaces/cavities, secretion

Muscle Elongatedcontractile cells

Moderateamount

movement

Connective Several types of fixed &wandering cells

abundant Support andprotection


3/47

1. EPITHELIALTISSUE1. EPITHELIALTISSUE

Epithelial tissues form boundaries betweenEpithelial tissues form boundaries betweenenvironments.environments.

made of sheets of tightly connected cells.made of sheets of tightly connected cells.

Types:Types:

Covering & lining epithelium.Covering & lining epithelium. Outer layers of skin.Outer layers of skin.

Linings of cavities.Linings of cavities.

LungsLungs

GIGI

Glandular epithelium.Glandular epithelium.

GlandsGlands


4/47

ROLE OF EPITHELIAROLE OF EPITHELIA Protection.Protection.

SkinSkin

Absorption.Absorption.

GIGI

Filtration.Filtration.

KidneyKidney

Excretion.Excretion.

Kidney & GIKidney & GI

Secretion.Secretion.

GlandsGlands

Sensory Perception.Sensory Perception.

Skin GISkin GI


5/47

CHARACTERISTICSOFCHARACTERISTICSOF

EPITHELIUMEPITHELIUM CellularityCellularity..

CloseClose--packed cellspacked cells

ContactsContacts tight.tight.

Tight junctions &Tight junctions & desmosomesdesmosomes Polarity.Polarity.

Apical surface & basal laminar surfaceApical surface & basal laminar surface

Connective tissue support (LAMINAConnective tissue support (LAMINA

PROPRIA).PROPRIA). AvascularAvascular but innervated.but innervated.

Regenerative.Regenerative.

LimitedLimited layer or layerslayer or layers


6/47

The Polarity of Epithelial CellsThe Polarity of Epithelial Cells

BASAL POLE

APICAL POLE

FREE SURFACE

LATERAL SURFACES


7/47

LAMINA PROPRIALAMINA PROPRIA

Connective tissue underneathConnective tissue underneathepitheliumepithelium

FunctionsFunctions-- supportsupport

-- nutritionnutrition

-- attachmentattachment

May form papillaeMay form papillae


8/47

Basal LaminaBasal Lamina

site of attachment of epitheliumsite of attachment of epithelium

Thickness varies with locationThickness varies with location

StructurelessStructureless, hyaline ground substance, hyaline ground substance

2 layers: lamina2 layers: lamina densadensa

laminalamina rararara

* reticular lamina* reticular lamina

COMPONENTSCOMPONENTS

Type IV collagenType IV collagen

LamininLaminin,, entactinentactin,, proteoglycanproteoglycan ((HepHep SO4)SO4)


9/47

Basement MembraneBasement Membrane

Basal lamina + reticular laminaBasal lamina + reticular lamina

PASPAS-- positive layer (lightpositive layer (light

microscopy)microscopy)


10/47

Basal LaminaBasal Lamina

Structural supportStructural support

barrierbarrier

Influence polarityInfluence polarity Regulate cell proliferation andRegulate cell proliferation and

differentiationdifferentiation

Pathway for cell migrationPathway for cell migration


11/47

INTERCELLULARADHESIONINTERCELLULARADHESION

& INTERC

ELLULAR

& INTERC

ELLULAR

JUNCTIONSJUNCTIONS

CommunicationCommunication

AdhesionAdhesion SealantSealant


12/47

Tight junction/Tight junction/zonulaezonulae

occludensoccludens

ApicalApical Close offClose off

intercellular spaceintercellular space

SEALSEAL


13/47

ZonulaZonula adherensadherens

Encircle cellEncircle cell

intercellularintercellular

adhesionadhesion NumerousNumerous actinactin

filamentsfilaments


14/47

Gap/Communicating junctionGap/Communicating junction

Lateral membraneLateral membrane

Made up ofMade up of

CONNEXONSCONNEXONS-- composed ofcomposed of

six gap unctionsix gap unctionproteins (proteins (connexinsconnexins))


15/47

exchange of molecules(


16/47

DesmosomeDesmosome/macula/macula adherensadherens

Complex discComplex disc-- shaped structureshaped structure

Firm attachment among cellsFirm attachment among cells

Supported by intermediateSupported by intermediatecytokeratincytokeratin filamentsfilaments


17/47

hemidesmosomehemidesmosome

Bind epithelial cell to basal laminaBind epithelial cell to basal lamina

Made up ofMade up of integrinintegrin plaquesplaques


18/47

microvillimicrovilli

Cytoplasm + plasma membraneCytoplasm + plasma membrane

Covered withCovered with GlycocalyxGlycocalyx coatcoat INCREASE SURFACE AREAINCREASE SURFACE AREA

SUPPORTED BY MICROFILAMENTSSUPPORTED BY MICROFILAMENTS


19/47


20/47


21/47

StereociliaStereocilia-- longlong microvillimicrovilli

-- non motile (non motile (epididymisepididymis))

-- increase surface areaincrease surface area


22/47

CILIACILIA--

MOTILE (5MOTILE (5--10 m long)10 m long)

MicrotubuleMicrotubule central paircentral pair

-- 9 pairs in periphery9 pairs in periphery Back and forth movementBack and forth movement

-- propellpropell

FLAGELLAFLAGELLA

-- seen in spermseen in sperm


23/47


24/47


25/47

CLASSIFICATIONOFCLASSIFICATIONOF

EPITHELIAEPITHELIA Layering.Layering.

SimpleSimple

StratifiedStratified

Cell shape.Cell shape.

SquamousSquamous

CuboidalCuboidal

ColumnarColumnar


26/47

ClassificationClassification


27/47

SIMPLE SQUAMOUS EPITHELIUMSIMPLE SQUAMOUS EPITHELIUM

Found:Found:

Body cavities (mesothelium).Body cavities (mesothelium).

CardioCardio--vascular and lymphatic systemsvascular and lymphatic systems(endothelium).(endothelium).

Smallest ducts of many glands.Smallest ducts of many glands.

Terminal respiratory ducts and air sacs.Terminal respiratory ducts and air sacs. Membranous labyrinth (except sensoryMembranous labyrinth (except sensory

areas); tympanic cavity.areas); tympanic cavity.


28/47

Squamous EpitheliaSquamous Epithelia


29/47

Simple Cuboidal EpitheliumSimple Cuboidal Epithelium

FOUND:FOUND:

Many glands; portions of their ducts.Many glands; portions of their ducts. Pigmented epithelium of retina;Pigmented epithelium of retina;

epithelioid covering of chorioidepithelioid covering of chorioid

plexus.plexus. Germinal layer of ovary.Germinal layer of ovary.


30/47

Cuboidal EpitheliaCuboidal Epithelia


31/47

Simple Columnar EpitheliumSimple Columnar Epithelium

Found:Found:

Stomach and intestine.Stomach and intestine. Many glands; portions of the ducts ofMany glands; portions of the ducts of

some glands; gall bladder.some glands; gall bladder.

Uterine tube and uterus.Uterine tube and uterus. Bronchioles.Bronchioles.


32/47

Columnar EpitheliaColumnar Epithelia


33/47



34/47

Transitional EpitheliumTransitional Epithelium


35/47

Pseudostratified EpitheliumPseudostratified Epithelium

Found:Found:

Larger ducts of glands opening ontoLarger ducts of glands opening ontoaa stratifiedstratifiedepithelial surface.epithelial surface.

Nasal cavity; trachea; bronchi.Nasal cavity; trachea; bronchi.

Much of male urethra; some ofMuch of male urethra; some offemale urethra.female urethra.

Most of male sexual duct.Most of male sexual duct.


36/47



37/47

Stratified Columnar EpitheliumStratified Columnar Epithelium

Found:Found:

Pharynx (in part); larynx (in part).Pharynx (in part); larynx (in part).

Urethra (in part).Urethra (in part).

Excretory ducts of salivary andExcretory ducts of salivary andmammary glands (in part).mammary glands (in part).

In general, where columnar orIn general, where columnar orpseudostratified epithelium meetspseudostratified epithelium meetsstratified squamous epithelium.)stratified squamous epithelium.)


38/47

Stratified Squamous EpitheliumStratified Squamous Epithelium Found:Found: Wherever there is exposure to friction, mechanical insult orWherever there is exposure to friction, mechanical insult or

drying.drying. SkinSkin Conjunctiva (in part)Conjunctiva (in part) CorneaCornea External acoustic meatusExternal acoustic meatus MouthMouth EsophagusEsophagus

AnusAnus Urethra (near outlet)Urethra (near outlet) Vagina.Vagina.


39/47

Squamous EpitheliaSquamous Epithelia


40/47


41/47


42/47

Stratified Cuboidal EpitheliumStratified Cuboidal Epithelium Testis tubules; vesicular (Graafian)Testis tubules; vesicular (Graafian)

follicles of ovary.follicles of ovary. Ducts of sweat glands; sebaceousDucts of sweat glands; sebaceous

glands.glands.

Intermediate zones of some regions,Intermediate zones of some regions,such as the urethra and conjunctiva.such as the urethra and conjunctiva.Urinary tract from kidney to urethraUrinary tract from kidney to urethra(transitional epithelium).(transitional epithelium).


43/47

Cuboidal EpitheliaCuboidal Epithelia


44/47

GOODDAYGOODDAY


45/47


46/47


47/47

Documents

Epithelial Tissue2