Histology• Studyoftissues• Tissues=agroupofcellsperformingacommonfunction
• Microscopicanatomy• Includeshowdifferenttissuesarearrangedtoformorgansandotherstructures
Ductusepididymis
4TissueTypes
• 4Typesoftissue– Epithelialtissue– Connectivetissue– Nervoustissue–Muscletissue
• CharacteristicDifferences– Proportionofcellstomatrix–Matrixcomposition– Cellfunction
EpithelialTissue• Composition– Oneormorelayersofcloselyadheringcells– Apicalsurfaceandbasalsurface– Restonabasementmembrane– Supportedbyconnectivetissues
• Function– Coverorgansurfaces– Formsecretorytissue– Formductsofglands
Classification
• Criteria– Numberofcelllayers– Morphologyofthesurfacecells
• Twomajorcategories– Simple(onelayer)– Stratified(twoormorelayers)
SimpleEpithelia
• General– Allcellstouchbasementmembrane• Exception:Pseudostratifiedcolumnar
• Categories– Simplesquamous– Simplecuboidal– Simplecolumnar– Pseudostratifiedcolumnar
SimpleColumnarEpithelium
• Foundin– Stomach– Smallintestines– Colon– Appendix
• Singlelayerofcells• Nucleiuniformlyarranged
GobletCellEpithelium
• Simplecolumnarepitheliumwithnumerousgobletcellspresent
• Gobletcellsproducemucus
• Foundin:– Smallintestine– Colon
PCCE
• Pseudostratifiedciliatedcolumnarepithelium
• Singlelayerofcells• Ciliapresentontheapicalsurface
Cilia
Ciliaarecomposedofmicrotubulesandprojectfromtheapicalsurface.Function:tomovethingsacrossthecellsurface
StratifiedEpithelia
• Generalcharacteristics– Upto20ormorecelllayers– Namedforshapeofsurfacecells
• Exception:transitionalepithelium• Stratifiedsquamous– Mostcommon– Exfoliation– Keratinizedtissue(cornified)– Nonkeratinized
StratifiedSquamousEpithelium
• Multiplelayersofcells
• Surfacelayercellsaresquamous
• Foundinareasthatexperiencefriction– Epidermis– Vagina
StratifiedCuboidalEpithelium
• Multiplelayersofcuboidcells
• Surfacelayerofcellsarecuboidal
• Foundin– Largeductsofglands
• Sweatglands• Pancreas
TransitionalEpithelium• Foundinsecretory
portionsoftheurinarysystem– Calyces– Ureters– Urinarybladder
• Distensibletissue(stretches)
• Epithelium“transitions”fromcuboidaltoalmostsquamousinappearanceastissuedistends
ConnectiveTissue
• Lesscells,moreECF(groundsubstance)• Variable,widelydistributed,mostabundant• Threecategoriesofmaturetissue– FibrousCT– SupportiveCT(bone,cartilage)– FluidCT(blood)
ConnectiveTissueFunctions
• Bindsorgans• Support• Protection– Physical– Immune
• Movement• Storage• Heatproduction• Transportation
FibrousConnectiveTissue:Components
• Cells– Fibroblasts–Macrophage– Leukocytes– PlasmaCells–MastCells– Adipocytes
• Fibers– Collagenous– Reticular– Elastic– Groundsubstance
TypesofFibrousConnectiveTissue
• LooseCT– Lotsofgroundsubstance
– Types• Areolar• Reticular• Adipose
• DenseCT– Fiberispredominantcomponent
– Types• Denseregular• Denseregularelastic• Denseirregular
AreolarConnectiveTissue• Cells
– Allsixtypes• Matrix
– Predominatelycollagenous– Someelastic/reticular
• General– Veryvascular– Looselyorganized– Varied– Underliesalmostallepithelial
tissue• Theseimagesareof
mesentery
ReticularConnectiveTissue
• Reticularfibersandfibroblasts
• Providessupportingframework(stroma),networkorlattice
• Found– Spleen– Lymphnodes– Thymus– Bonemarrow
AdiposeTissue
• Adipocytesmostabundantcelltype
• SupportedbyareolarCT,reticularCT,bloodvessels
• Function:– Energystorage– Insulates– Supports– Cushionsshock
• Whitefatvs.Brownfat
DenseRegularConnectiveTissue
• “regular” arrangementoffibroblastandcollagenfibers– Closelypackedparallelcollagenfibers+fibroblasts
– Formbundlesofcollagenfibers
• Foundintendons
DenseRegularElasticConnectiveTissue
• Largeamountofelasticfibersinparallelarrangement
• Elasticfiberscanstretch1½timestheirlengthandthenrecoil
• Provideselasticity• Found
– Ligaments– Largearteries– Bronchialtubes
DenseIrregularConnectiveTissue
• Collagenfibersinrandomarrangement+fibroblasts
• Found– Reticularlayerofdermis– Protectivecapsulearoundorgans
– Fibroussheetaroundbones,etc.
• Similartoareolar,butless“open” space
Cartilage
• Flexiblematrix• Avascularexceptwhentransformingtobone
• Externalear,tipofnose,larynx
• Cells– Chondroblasts
• secretematrix
– Chondrocytes• trappedinlacunae
• Threetypes– Hyaline– Elastic– Fibrocartilage
HyalineCartilage• Matrix
– smooth,frictionless– mixofcollagen,elastin,
chondroitin(aglucosaminoglycan)• Cells
– Cellnests• Usuallycoveredby
perichondrium– DenseirregularCTcovering– innerlayerproducesnew
chondrocytes• Examples:
– Costalcartilage– Nasalseptum– C-ringcartilageof
trachea– Fetalskeleton
ElasticCartilage
• Matrix– Web-likemeshofelastic
fibers– Appearanceoffur
• Perichondriumalwayspresent
• Examples:– Pinnaofear– Epiglottis
Fibrocartilage
• Characteristics– Parallelcollagenfibers– Rowsofchondrocytesinlacunae
– Noperichondrium• Examples– Pubicsymphysis– Intervertebraldiscs– Menisciofthesynovialjoints
CompactBone• Novisiblespaces• Densecalcifiedtissue• Found
– Externalsurfaceofallbone– Shaftsoflongbones
• Tissuearrangedintoosteons– Concentriclayersofmatrix
andosteocytessurroundingacentralcanal
• Periosteum
SpongyBone
• Found– Headsoflongbones– Middlelayerofroofingbonesofskull
• Namedforappearance• Tissuearrangedintotrabeculae(fusionofspicules)
• Bathedinredmarrow
FluidConnectiveTissue:Blood
• Plasma+formedelements
• Erythrocytes• Leukocytes– Neutrophils– Basophils– Eosinophils– Monocytes– Lymphocytes
• Thrombocytes