histology of the special sense

7/23/2019 Histology of the Special Sense

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HISTOLOGY OF THEHISTOLOGY OF THE

EAREAR



THE EAR

EarSensory organ functions as an auditorysystem for sound perception and as avestibular system for balance

General Structure

Eternal Ear!iddle Ear

Internal Ear



EternalEternalEarEar

• Pinna

–Auricle –Elastic cartilage ece"t in auricle lobule

–#overed by $air%bearing s&in $airfollicles' s(eat gland and sebaceus

gland

–Function To collect and am"li)essounds



• External Acoustic Meatus

–An air%)lled tubulae s"ace *+ mm totym"anic membrane

–Lined by s&in $air follicles' sebaceousgland , ceruminous glands

– T$e outer *-. elastic cartilage

– T$e inner /-. tem"oral bone



!iddle Ear!iddle Ear

• TympanicMembrane

• oval' grayis$

• . layers – Outer layer covered

by s&in' strati)eds0uamous e"it$elium'no glands' no $air

– !iddle layer Fibrocollagenous

su""ort tissue

– Inner layer lined bylo( cuboidal

e"it$elium



• Auditory ossicles• . bones malleus' incus' sta"es

• * muscles m tensor tim"any , m1 sta"edius

• #onvert t$e sound (aves to mec$anical vibration in"erilmfe of t$e internal ear

• Mastoid air cells• An air%)lled s"aces in t$e mastoid bone



• Tympanic cavity• 2 !iddle ear cavity• An air%)lled s"ace lined by lo( cuboidal e"it$elium• #ommunicates (it$ mastoid air cells



Auditory tube (eustachian tube)• #onnects t$e middle ear to naso"$aryn• A narro( c$annel .1+ cm long• Lined (it$ cilliated "seudostrati)ed columnaire"it$elium /-+ com"osed of goblet cells

• 3entilating t$e middle ear• E0uali4ing t$e "ressure ot t$e middle ear (it$atmos"$ere "ressure



Internal Ear

Consists of 5• * labyrint$ine com"artments

– 6ony labyrint$ – !embranous labyrint$

• . 7uid%)lled s"aces – Endolym"$atic s"ace – 8erilym"$atic s"ace – #ortilym"$atic s"ace



ony !abyrinth• #om"osed of . cavities

vestibule' semicircular

canals' coc$lea• Lined by "eriosteum' )lled

by "erilym"$

"estibule

Oval Oval (indo(

Semicircular canals . canals anterior'

"osterior , lateral

E"anded at t$e end ofeac$ canals close to t$evestibule am"ulla



Cochlea

Contains 3 spaces vestibular cavity (scala

vestibuli), cochlear duct

(scala media) & tympanic

cavity (scala tympani)

wound in a spiral shape

The central spiral of bone

within the cochlea

Modiolus

At the ape the vestibular

& tympanic cavity connect

at an openin!

"elicotrema Helicotrema



!embranousLabyrint$

"estibular labyrinth – . semicircular ducts

– 9tricle , saccule

– T$in (all' trans"arent

• Semicircular ducts – . ducts' e"and at t$e end

ampulla

– A raised mass of e"it$elialtissue in am"ulla crista

ampullaris contains ofsensory , su""orting cells

– A gelatinous mass ofetracellular materialcovering t$e crista cupula



• #tricle

• Ends of semicircularducts

• Lateral (all macula of utricle

• Saccule

• 9triculosaccular duct connect t$e utricle, saccule

• Endolym"$atic duct saccule andendolym"$atic sac

• Reuniens duct saccule (it$coc$lear duct

• !edial (all maculaof saccule



Macula – #ontains of sensory

$air cells , su""ortingcells

– * ty"es of sensory cells

– Ty"e / $air cells

– Ty"e * $air cells

– T$e sensory ,su""orting cells covered by a gelatinousmass of etracellularmolecules otolit$ic

membrane

– :etect t$e gravity and

static "osition



Cochlear !abyrinth – #ontains t$e coc$lear ducts' )lled (it$ endolym"$ – :ivides t$e coc$lear canal into . com"artments 5 Scala media'

scala vestibuli , scala tym"ani – Scala media is a triangular s"ace' attac$ed to osseous s"iral

lamina – T$e u""er (all of scala media Reissner;s <3estibular= membrane – T$e lateral (all of scala media Stria vascularis – T$e lo(er (all 6asilar membrane – T$e s"iral organ of corti rests on t$e basilar membrane , is

overlain by t$e Tectorial membrane



• Tectorial membrane – Attac$ed medially tot$e modiolus

– Lateral edge attac$esto t$e organ corti by

stereocilia of t$e $aircells

– Formed frometracellular material



• $r%an of Corti – #om"osed of e"it$elial

su""ort cells and sensory

$air cells – !edially it rests on osseous

s"iral lamina' laterally on t$ebasilar membrane

– * grou"s of $air cells

• Inner $air cells , Outer$air cells se"arated byt$e inner tunnel <tunnel ofcorti=

– T$e $air cells are surroundedby e"it$elial su""ort cells

• 8ilar cells surround ,su""ort t$e inner tunnel

• 8$alangeal cells su""ortt$e $air cells



atari Tod&a #mar

HISTOLOGY OF THE EYEHISTOLOGY OF THE EYE



Spherical structure, ± 25 mm in diameter Suspended in the bony orbital socket 6 extrinsic muscles

Wall of the eye 3 concentric layers Fibrous tunic Vascular tunic

er!e tunic

THE EYE



A t$ic& )brous layer' covers t$e"osterior +-> of t$e eyeball

:ivided into . layers 5 E"isclera Eternal layer Loose connective tissue ad?acent to t$e

"eriorbital fat

Stroma <Substantia "ro"ria= 2 Tenon;s ca"sule #om"osed of dense net(or& of t$ic&

collagen )bers

S#LERAS#LERA



• Lamina Fus$cae Inner as"ect' ad?acent

to t$e c$oroid #ontains of t$inner

collagen , elastic)bers

!elanocyte

'unction 8rotects , maintainst$e s$a"e and t$evolume of t$e

eyeball



• Transitional 4onebet(een t$e cornea, sclera

• /1+ @ * mm (ide' /mm t$ic&

• Iridocorneal angle a""aratus for t$e

out7o( of t$ea0ueous $umor trabecular mes$(or&

#orneoscleral Limbus#orneoscleral Limbus



Trans"arent'1+ mm t$ic&at t$e center'avascular' +layers

#ornea



Cornealepithelium

B Con%&eratini4ing

s0uamous e"it$eliumB 6asal cell layer givesrise to +%D su"er)ciallayers

B Free nerve endingsterminate in t$ise"it$elium

B Ad$eres to t$e ad?acentcells by desmosomes



oman*s Membrane

– %/ m t$ic&

– #om"osed of )necollagen )brils

– 6arrier to t$e s"readof infection

– Cot regenerate

Corneal stroma

B #onstitutes oft$e corneal t$ic&ness

B #om"osed of about> t$in lamellae

B Eac$ lamellae consistof "arallel bundles ofcolagen )brils



+escemet membraneB 6asal lamina of

endot$elial cellsB HomogenB Elastic' trans"arentB D @ / m

Corneal endotheliumB A single layer ofs0uamous cells

B !etabolic ec$angebet(een t$e cornea, a0ueous $umor

B 8recise regulation oft$e (ater content oft$e stroma maintain t$etrans"arency

B 8$ysical , metabolicc$anges corneal

s(elling



T$e most anterior "art of t$e vascular tunic'

forms a contractile dia"$ragm in front of t$elens' a circular a""erture <"u"il= c$anges in si4ein res"onse to t$e lig$t intensity1 Eye colour isdetermined by t$e relative number ofmelanocytes

IRISIRIS



#om"osed of J layers Anterior limiting membrane

Fibroblastic , melanocyte cells

Stroma Loose )brocollagenous su""ort tissue 6lood vessels' nerve' melanin "igment S"$incter muscle of t$e "u"il



Epithelial layer B Anterior non,pi%mented

epithelium B :ilator "u"illae muscle

B Posterior pi%mentepithelium

B Faces t$e "osterior c$amber oft$e eye



• Triangular s$a"e

• Etends from t$e base of t$e iris tot$e ora serrata

• * anatomical regions – 8ars "lica

– 8ars "lana

• Function 5 – A0ueous $umor "roduction

– Acomodation "rocess

#illiary 6ody



• T$e layers are similarto t$e iris

• #onsist of 5

– Stroma• Outer layer ofsmoot$ muscle cilliary muscle

– !eridional<longitudinal"ortion=

– Radial <obli0ue"ortion=

– #ircular "ortion

• Inner vascularregion etendsinto t$e cilliary

"rocess – #ontinuous (it$

t$e vascularlayer of t$ec$oroid



• E"it$elial layers – . "rinci"al functions

• Secretion of a0ueous $umor• 8atici"ation in blood a0ueous barrier

• Secretion , anc$oring t$e 4onula )bers

– T$e inner cells layer non%"igmented

– T$e outer cells layer "igmented



• :ar&%bro(n vasculars$eet' 1*+ mm t$ic&"osteriorly' 1/ mmt$ic& anteriorly

• Lies bet(een t$e sclera

, retina• Su""orts t$e retina• #ontains of 5

– Su"rac$oroid lamina• . m t$ic&• Loose connective

tissue – #$oroidal stroma

• Cumerous venules ,arterioles

• Haller layer <outer "art=• Sattler layer <inner "art

#HOROI:

Ch i ill



ChoriocapillaryB #a"illary layer su""orting t$e dee" layer of t$e retina

B :iameter J @ > m

B T$in (all

-. ruch*s membraneB /%J m t$ic&

B Interface bet(een t$e c$oroid , t$e retinal "igment e"it$elium



/0 layers/1 Retinal "igment

e"it$elium*1 8$otorece"tor cells

.1 Outer limiting membraneJ1 Outer nuclear layer+1 Outer "leiform layer>1 Inner nuclear layer

D1 Inner "leiform layer1 Ganglion cells1 Cerve )ber layer/1Inner limiting membrane

RETICA



Retinal Layers



Retinal 8igment E"it$elium

$ ll



8$otorece"tor cells



• !E1S Trans"arent' avascular'biconveSus"ended bet(een t$e edgesof cilliary body 4onula )bers mm in diameter' .1+ mm t$ic&

Capsule• A t$ic& basal lamina• 8roduced by t$e anterior lens

cells Subcapsular epithelium

#uboidal layer of cells Only on t$e anterior surface of

t$e lens

!ens 2bers :erived from subca"sular

e"it$elial cells

REFRA#TI3E !E:IA OF THE EYE



• "itreous ody

– 6et(een t$e lens , t$e retina – Trans"arent gelatinous structure – Attac$ to t$e surrounding structures – !ain "ortion is $omogenous gel containing

(ater' collagen' $yaluronate acid – Avascular



• Con&unctiva – A translucent membrane – Etends from corneoscleral limbus % internal

surface of t$e eyelid

– * layers• Strati)ed columnar e"it$elium

– Goblet cells mucin

• Lamina "ro"ria – Loose connective tissue

– 6lood vessels , lym"$atic vessels

A##ESORY #O!8OCECTS OF THE EYE

P l b



• Palpebra – 9""er , lo(er eyelid – 8rotection of t$e eye – #ontains of 5

• S&in• Orbicularis oculi muscle• Tarsal "late• #on?unctiva• Glands

– !eibomian glands

# Sebaceous ty"e# Oily layer of t$etear )lm

# Embedded in t$etarsal "late

– Glands of Keis# Sebaceous glands

– Glands of !oll# A"ocrine s(eat

glands – Glands of rause

# Forni con?unctiva – Glands of Molfring

# Above t$e tarsal"late

! i l t



!acrimal apparatus

• !acrimal %lands – 9""er lateral side of t$e

orbit

– * "arts 5 orbital ,"al"ebral "arts

– / @ * ducts

– Several se"arate

lobules of tubuloacinarserous glands

– :rains into t$e u""erforni

– Mas$ over t$e surface

of t$e eye



• Tears drain from t$e eyet$roug$ lacrimal "uncta

• Lacrimal canaliculi atmedial angle'

• !erge into common

lacrimal duct• O"en into lacrimal sac'

"seudostrati)ed ciliatede"it$elium

• #ontinuous to

nasolacrimal duct o"ento nasal cavity belo( t$einferior turbinate



34ST$!$G5 $' T3E34ST$!$G5 $' T3E

1$SE1$SE



1ASA! CA"4T5

• 8aired c$ambersse"arated by abony ,cartilaginousse"tum

• :ivided into .regions 5

– 3estibule – Res"iratory

segment – Olfactory

segment



"estibule of the 1asal Cavity"estibule of the 1asal Cavity

• #ommunicates anteriorly (it$ t$e eternalenvironment

• Lined (it$ strati)ed s0uamous e"it$elium

• #ontains of 5 – StiN $air <vibrissae= entra"s t$e large "articles

– Sebaceous glands

– S(eat glands



• Located at t$e dome of eac$ nasal cavity

• Lined (it$ olfactory mucosa

• Lamina "ro"ria of olfactory mucosa

directly contigous (it$ t$e "eriosteum – #ontains of blood , lym"$atic vessels' nerve ,

olfactory glands <6o(man glands=

– T$e secretion of t$e glands solvent in ($ic$

odorous substances dissolve

• Olfactory mucosa "seudostrati)edcolumnar e"it$elium

$lfactory Se%ment of the 1asal$lfactory Se%ment of the 1asal

CavityCavity



Olfactory e"it$elium

#om"osed of 5• Olfactory

rece"tor cells – 6i"olar neurons

"osses an a"ical

"ro?ecting bearingcilia as a rece"tor

– A"ical "ole dendritic "rocessabove t$ee"it$elial surfaceas a &nobli&estructure olfactory vesicle



• Supportin%

(Sustentacular) cells – !ost numerous cells – Cuclei more a"ical

"osition – !icrovili on t$e a"ical

surface – Function 5 metabolic ,

"$ysical su""ort to t$eolfactory cells

• asal cells – Stem cells ne(

olfactory cells ,su""orting cells

• rush cells – 9ncommon – Similar to t$e res"iratory

e"it$elium



34ST$!$G5 $' T3E34ST$!$G5 $' T3ES641S641



41TEG#ME1T

• T$e largest organ of t$e body• Etensive organ forms t$e eternal

covering of t$e body

• #onstituting /+%* of total body mass

• #onsist of * "rinci"les layers 5 – Outer e"it$elial layer e"idermis

– :ee"er connective tissue layer :ermis



S

• 8rotective s&in layer in contact(it$ t$e eternal environment

• eratini4ed' strati)ed s0uamouse"it$elium

• + layers 5 basale' s"inosum'granulosum' lucidum' corneum

• !ain cells are &eratinocytes eac$ layer $ave a c$aracteristica""earance' "roduce &eratin

• Avascular



a. Stratum asale – 2 stratum

germinativum – Single layer cells'cuboidal or lo(columnar

– !itotically active cells – Stem cells of t$e

e"idermis ne( cell oft$e s&in &eratinocyte

– * ot$er cells ty"e 5• !elanocytes

– :endritic cells – 8roduce t$e dar& bro(n%

blac& "igment of t$e s&in• !er&el cells

– Sensory cell



b. StratumSpinosum – * @ > cells layer t$ic& – #uboidal or lo(

columnar – T$e cells synt$esi4e

large amount of &eratin)ament

– !ature cells move tot$e surface' increase insi4e and become7attened in a "lane"arallel to t$e surface

– A s"eciali4ed cell ofimmune system Langer$an;s cells

derived from bonemarro( stem cells "art of t$e "eri"$eralimmune system



c1 Stratum Granulosum – T$e most su"er)cial

layer of t$e non%&eratini4ed "ortion oft$e e"idermis

– *%+ cells layer t$ic&

– eratinocytes * ty"esof granules

• erato$yaline granules• !embrane%coating

granules <lamellarbodies=

– As t$ese cells continueto diNerentiate

degrade most of ma?orcell organelles leavest$e &erato$yaline toform t$e &eratin

d Stratum !ucidum



d. Stratum !ucidum – T$ic& s&in – /st anucleate cell

layer of t$e s&in

– In t$e very t$ic& s&in – J @ D cells layer t$ic& – #yto"lasmic

organelles disa""earas t$e cells gradually)lls (it$ &eratin

e. StratumCorneum – T$e most su"er)cial

layer – T$e most

diNerentiated layer – + @ / cells layer t$ic& – :o4ens of cell layer

t$ic& on t$e "almar ,"lantar surface

+E7M4



+E7M4S

• #onnective tissue directly under t$e e"idermis• #om"osed of collagen , elastin )bers• #ontains of 5

– Etensive net(or& of blood vessels' s(eat glands'nerve' lym"$atic vessels' $air s$aft , sebaceous glands

• * layers 5 – 8a"illary dermis – Reticular dermis



/. Papillary +ermis – Interface (it$ t$e

e"idermis

– #onsist of irregular sets ofinterdigitating structures

– T$e do(n(ard "ro?ect rete"egs

– T$e u"(ard "ro?ect dermal "a"illae

– #ontains of manyca"illaries

8. 7eticular +ermis – T$ic& layer

– T$e )bers are t$ic&er t$ant$e "a"illary dermis – Hig$ vascular' nerve

bundles' s(eat glands' $airfollicles



3A473A47

• A com"le structures'originates in a $airfollicle

• Eac$ $air s$aftcom"osed of . layers 5 –

!edulla• #entral "art of t$es$aft

• Only in t$ic& $airs

– #orte• 8eri"$eral to t$e

medulla

• #uboidal cells – #uticle of t$e $air

s$aft• S0uamous cells• Outermost layer of

t$e $air



Hair Follicle

– :ivide into .

segments• Infundibulum

– Surface % o"ening ofsebaceous gland

– 8art of "ilocebaceous

canal route for t$edisc$arge of sebum

• Ist$mus

– Infundibulum %insertion of t$e

arrector "ili muscle• Inferior segment

– Gro(ing follicle' formt$e $air bulb



4nternal root sheath• . layers

– #uticle• S0uamous cells• Faces t$e $air s$aft

– Huley;s layer

• Single or doublelayer of 7atennedcells

– Henle;s layer• Outer single layer of

cuboidal cells

External root sheath



1A4!• Cail "lates Hard &eratin

• Cail root "roimal "art of t$e

nailburied in a fold e"idermis e"onyc$ium

• #rescent s$a"e near t$e root lunula

• Free edge of nail "late $y"onic$ium

G!A1+



G!A1+S

Sebaceous Glands – M$ole body ece"t t$e "almar , "lantar surface – In association (it$ $air follicles – T$e secretions em"ty into t$e emerging $air s$aft t$roug$

"ilosebaceous duct – Tubuloalveolar s$a"e – Secrete by t$e $olocrine mec$anism

S t Gl d



Seat Glands

• Eccrine S(eat Glands – Inde"endent

structures' notassociated (it$ $airfollicles

– * segments 5• secretory segment

– . cells ty"e

– #lear cells , dar&

cells – !yoe"it$elial cells

• duct segment – Strati)ed cuboidal

e"it$elium

– T$e cells aresmaller , dar&er

t$an secretory"otion

– Smaller diameter

– Co myoe"it$elialcells

– T$e secretion 5 (atery'$y"otonic' odor%free

A i S t Gl d



• A"ocrine S(eat Glands – Found in ailla ,

"erianals area

– Functional in "uberty

– Larger t$an eccrines(eat glands

– Secretory "ortion• Mider lumen t$an eccrine

glands

• / cell ty"e

– Ecretory "ortion• As a "art of t$e

"ilosebaceous duct

– T$e secretions• "rotein , li"id

com"onents

•Odorless in t$e time ofsecretion

• T$roug$ bacterial actionon t$e s&in surface odorc$aracteristic of t$es"esi)c location of t$eglands



34ST$!$G5 $' T3E34ST$!$G5 $' T3E

T$1G#ET$1G#E



T$1G#E

B Muscular or%an covered in s9uamous epitheliumB 4nferior surface covered by non,:eratini;in% strati2eds9uamous epitheliumB #pper surface covered by thic: :eratini;in% strati2eds9uamous epithelium

#pper



#pperSurface

• :ivided into *main 4one 5

– Anterior *-.

– 8osterior /-.

– Se"arated by 3%s$a"ed line<sulcus

terminalis= of >%/ dome s$a"e"rotrusions



• T$e surface e"it$elium of anterior*-. of t$e tongue raised in seriesof elevation papillae

• . ty"es "a"illae 5 – Filiform "a"illae

– Fungiform "a"illae

– #ircumvallate "a"illae lined on 3%

s$a"ed line



• Filiform "a"illae

– T$e smallest' mostnumerous in $umans

– Found all over t$eu""er surface of *-.

anterior "art – Tall' narro('

&eratini4ed

– Co taste buds' serveonly mec$anical role



• 'un%iform Papillae – !us$room s$a"e' scatteredrandomly among t$e )liform "a"illae

– 8rimary , secondary "a"illae

– Cumerous at t$e ti" of t$e tongue

– Taste buds are "resent• Anterior ti" s(eet taste

• 6e$ind t$e ti" , along t$e lateral border salty taste

• Circumvallate



C cu a a epapillae – Large' dome%s$a"e

structures on t$e sulcusterminalis

– Surrounded by cleft

– #ontains numeroustaste buds

– Cumerous "rimary ,

secondary "a"illae – von Ebner;s gland

em"ty t$eir secretioninto t$e base of t$ecleft

– T$e secretion 7us$est$e material from t$ecleft to enable t$e tastebuds to res"ond ra"idlyin c$anging stimuli



'oliate papillae – Cumerous in animals

– Lateral edge of t$etongue

– In younger found ont$e "ost%lateral surface

– In elderly obliterate

– Taste 6uds

– 8rimary "a"illae long, large

– Secondary "a"illaer

very $ig$ – Small serous gland

em"ty into t$e cleft

Taste



Tasteuds• Sensory receptor for taste

• $nion,li:e shape• $ccupies the fullthic:ness

of epithelium

• Small openin% ontoepithelial surface tastepore

• < principal cell typesneuroepithelial (sensory)cells= supportin% cells=basal cells

• Sensory cells mostnumerous cells= turnoevertime /0 days

• Supportin% cells lessnumerous= do not sinapseith the nerve cells

• asal cells basal portion=stem cells for the 8 othercells type



• Taste is c$aracteri4ed as c$emical sensation substance contained in food interact (it$ tasterece"tors

• React to + basic stimuli s(eet' salty' bitter' sour, PumamiQ

• 9mami taste of certain amino acids <e1gglutamate' as"artate=

• S(eet stimuli ti" of t$e tongue

• Salty stimuli "osterolateral to t$e ti"

• Sour stimuli more "osterolateral to t$e ti"

• 6itter , umami stimuli circumvallate "a"illae

S&eletal muscle is arranged in many directionslongitudinally



longitudinallyverticallytransverselyobli0uely

Great mobility to mani"ulate food around t$e mout$ for 5ecient fragmentationmoving fragmented food bac&(ard "rior to

s(allo(ingcontrol t$e tongue movement for s"eec$



8osterior /-. of t$e tongue• 2 Root of t$e tongue

• Co "a"illae

• #overed by non%&eratini4ingstrati)ed s0uamous e"it$elium

histology of the special sense

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