Histo Topic List Final Version

7/25/2019 Histo Topic List Final Version

1/38

Histology

1. Characteristics of epithelial tissue (Fares and Jamal)

Epitehelium is tissue organized as attached sheets of cells which line orcover and form tubular structures within organs.Location Covers all body surfaces/lines cavitary organs and forms exocrine& endocrine glands.hey originate in all ! embryonic layers" Endoderm #igestive$ respiratory$thyroid %esoderm Endothelium$ %esothelium

Ectoderm Epidermis$ adenohypophysisComposed of compact mass of specialized cells EC matrix contains smallamount of cells with a highly organized basement membrane.

Characteristics' various cell shapes and functions$ avascular$ (nnervated$renewable$ and can undergo metaplasia.)hapes" *latted +s,uamous-$ cuboidal and columnar*unctions" protection$ absorption$ transport of material at surface & gasexchange$ secretion$ excretion and contraction.

. Characteristics of epithelial tissue. +ohn-

Location0covers all body surface/lines cavitary organs

0forms exo' and endocrine glands.

Origin ' in all ! embryonic layers0endoderm" digestive$ respiratory epithelium$ thyroid0mesoderm" endothelium$ mesothelium0ectoderm" epidermis$ adenohypophysis

Composed of0Cells" compact mass of specialized cells0Extracellular matrix"0small amount

0highly organized ' basement membrane

Characteristics:01arious cell shapes and functions

Cell shapes" 2attened$ cuboidal$ columnar

he nuclear form often corresponds to the cell shape

0 3vascular


2/38

0 (nnervation

free nerve endings un'myelinated axons

depends on location of the epithelium and its exposure to stimuli

0 4enewal

Epithelia continuously renew their cell population

#i5erent rates" fastest small intestine$ slowest' s6in0 %etaplasia7transformation into another type of mature epithelium$ in pathologicalcircumstances

issue has the ability to transform into a di5erent tissue if something

goes wrong. Can be reversed if the stimulus goes away.

E.g.

2. Polarity of epithelial tissue and epithelial cell. Differences between apical andlatero-basal domains of epithelial cells (Fares and Jamal)

8olarity is due to organelle distribution and membrane protein distribution+membrane domain-3pical domain" 8roteins enzymes$ transporters$ channels Lipids Cholesterol$ sphingomyelin9aso'lateral domain" 8roteins :a;/


3/38

=. 8olarity of epithelial tissue and epithelial cell. #i5erences betweenapical and latero'basal domains of epithelial cells +ohn-

Cells will always have an apical pole$ a lateral pole and a basal pole

he free or apical domainis always directed toward the exterior

surface or the lumen of an enclosed cavity or tube. he lateral domaincommunicates with ad>acent cells and is

characterized by specialized attachment areas.

he basal domainrests on the basal lamina anchoring the cell tounderlying connective tissue.

hey are ?polarized@"

#epending on the di5erent tissue types$ di5erent things go on at each

pole polarized distribution of organelles and membrane proteins,

depending on cell function

Organelle polarity in cells:Type of cell 3pical pole 9aso'lateral pole3bsorptive cell %itochondria

3ctive absorptionre,uires 38

)ecretory cell Aolgi apparatus 7Bsecrete vesicles at theapical pole

4E4 located here+protein synthesis:ucles located below

Polarity of membrane proteins and lipids membrane domains:

Component 3pical domain 9aso'lateral domain8roteins 0Enzymes

0ransporters0Channels

0:a;/


4/38

04eceptors03dhesion proteins

Lipids 0Cholesterol0)phingomyelin

08hosphatidylcholine08hosphatidylinositole

. !peciali"ations of the apical domain (cilia# micro$illi# stereocilia)%

structure# ultra structure# locali"ation and functions (Fares and Jamal)Cilia )eperated into motile and primary cilia- ' 8rimary cilia found in nearly every cell of the body$ movessubstances using passive 2ow of 2uid$ also can function as sensory antennae ' %otile cilia found in epithelia which are involved in transporting$uses active movement ' 9oth types of cilia possess axoneme$ basal bodies and intra 2agellartransport system)tereocilia 3ctin laments bundle anchored into a terminal web ' Located in male reproductive system +absorptive function- andinner ear$ where it *unctions as mechanoreceptors%icrovilli 3lso actin laments bundled into terminal web ' 8resent in many epithelial cells

' increases absorptive surface of cells ' 1isible in L% as striated/brush border

. )pecializations of the apical domain +cilia$ microvilli$ stereocilia-")tructure$ ultra structure$ localization and functions

(n many epithelial cells$ the apical domain exhibits special structural surfacemodications to carry out specic functions +shown in table below-

!icro"illi and stereocilia"

Types ofcilia:


5/38

&. !peciali"ations of the latero-basal domain (Fares and Jamal)*uc6 this bullshit ,uestion.

D. )pecializations of the latero'basal domain +ohn-#omain )pecializationsLateral Celltocell complexes:

#$ ight >unctions%$ 3nchoring >unctions

wo types +on lateral pole-

zonula adherens

macula adherens or desmosome$

&$ Aap >unctions

9asal Celltoextracellular matrix 'unctionsanchor the cellto the extracellular matrix

. *ocal adhesions=. emidesmosomes

. ight unctions"

(mpermeable and allow epithelial cells to function as a barrier.

Limit the mo"ement of (ater and other moleculesthrough theintercellular space 7B maintain physicochemical separation of tissuecompartments.

Pre"ent the migration of lipids and specialized membraneproteinsbetween the apical and lateral surfaces$ 7B maintain theintegrity of these two domains

=. 3nchoring unctions"8rovide lateral adhesions between epithelial cells$ using proteins that lin6into the cytos6eleton of ad>acent cells.) zonula adherens +pl.$zonulae adherentes-$ which interacts with the

networ6 of actin laments inside the cell and) macula adherens +pl.$ maculae adherentes- or desmosome$ whichinteracts with intermediate laments

!. Aap >unctions8ermit the direct passage of signalling molecules from one cell to another.

F subunits +connexions- 7B connexons 7B gap >unction

3llows cells to function together


6/38

+9asal pole-. *ocal adhesions

3nchors actin of the cytos6eleton in the cell to the extracellular matrix

=. emidesmosomes3nchors intermediate laments of the cytos6eleton to the extracellularmatrix

'. amina basalis and basement membrane

9asal lamina" )heet of EC material between epithelial and connective tissue. Gnly visible in E% =H'HHnm thic6 Consists of lamina densa+brilar networ6- and lamina lucida

Composed of molecules secreted by epithelial cells" type D collagen$ A8@sand 8A@s9asement membrane is a thic6 structure formed by basal lamina andreticular lamina.(t anchors down the epithelium to the loose connective tissue underneath9oth basal lamina and basement membrane are specializations of thebasolateral pole

. Classification of co$erin* epithelia

9ased on number of cell layers"' )imple' )tratied

9ased on cell shape"' ),uamous +2attened-' Cuboidal' Columnar

ypes include" ' )imple/stratied s,uamous/cuboidal/columnar ' 8seudostratied ' ransitional/urothelium

I

+. !imple epithelia% characteristics# locations# functions

)imple s,uamous" located in endothelium$ mesothelium$ bowmans capsuleetc. *unctions include ltration$ di5usion$ osmosis$ secretion+serosa-)imple cuboidal" Located in 6idney tubules$ excretory ducts of excretoryglands and covering


7/38

Epithelium of ovary *unctions are secretion and absorption)imple columnar" Located in digestive tract$ fallopian tubes$ excretory ductsof salivary glands as apical surface specializations +cilia and microvilli-$ for

absorption$secretion

,. Pseudostatified epithelium% characteristics# locations# functions

Located in respiratory epithelium and male reproductive system*unctions include secretion +goblet cells-$ clearance +ciliated cells- andabsorption +stereocilia-(t has apical surface specializations" cilia and stereociliaConstists of single layer of cells with nuclei similar to stratied epithelia(t gives the impression of more than one layer of cells but it@s a single layer

resting on basal lamina. his is because the nuclei are disposed at di5erentlevels.

. !tratified suamous /eratini"ed epithelium% characteristics# location# functions#

)ame as stratied s,uamous +layer of 2at cells- but with dead 6eratinizedcells at surface*orms the epidermis of s6in8rotects underlying tissues in areas sub>ect to abrasion

10. !tratified suamous non /eratini"ed epithelium% characteristics# location#functions#

)ame as stratied s,uamous +layers of 2at cells- but has living$ nucleatedcells at surfaceLocated in digestive tract from mouth to esophagus$ and also in the vaginaand anterior cornea8rotects areas sub>ect to abrasion

11. !tratified cuboidal and columnar epithelia% characteristics# locations# functions

)tratied cuboidal" ' located in sweat glands and excretory duct' functions are protection and secretion' consists of layers of cuboidal cells

)tratied columnar" ' located in ocular con>unctiva and large ducts of salivaryglands

' *unctions are protection and absorption' Layers of columnar cells


8/38

12. ransitional epithelium% characteristics# location# functions

Consists of basal cells$ rac6et shaped cells and umbrella'li6e cellsLocated in urinary excretory tract

*unctions" stretches allows organs to distend 8rotective osmotic barrier

1. ndocrine *landular epithelium% classification

Alandular epithelium is one or more epithelial cells highly specialized for

secretion.)ecretory process has D phases" 3ssimilation$ synthesis$ storage andsecretion.Endocrine glands have no connection with the surface completelysurrounded by conn tissueEliminates secretory product directly into blood streamhey can be classied based on"' Cell grouping cords$ follicles$ islets$ isolated cells' Chemical structure of secretory product small polypeptides$ cholesterol' %oment of release of secretory product immediate release$ after storage-4ange of action of secretory product autocrine +on itself-

' 8aracrine +small range neighbouring cells-' Endocrine +at distance-

1&. 3ocrine *landular epithelium% classification4 e3amples

Exocrine glands are in contact with free surface of epithelium by an excretoryduct.Eliminates product through a ductClassication"' 9y structure" )imple ubular Lieber6uhn Aland

' Coiled tubular' 9ranched tubular' acinar' 9ranched acinar

' 9y chemical composition of secretory product" %ucous gland +product richin A8@s$ viscous- )erous gland +proteinsecreting cell-


9/38

%ixed gland' 9y secretion mechanism merocrine +exocytosis of stored granules-

' 3pocrine +secretion of both product and apicalcytoplasm-

' olocrine +destruction of entire cell during secretion-

1'. Cells speciali"ed for protein synthesis (serous cells)

ype of exocrine cell8olarity" basal pole rich in 4E4 Aolgi above round nucleus in central area 3pical pole with zymogen granules)ecretion" enzymes +pancreas$ salivary glands- ormones +parathyroid ' 8-

1. Cells speciali"ed for *lycoprotein synthesis (mucous cells)

' Exocrine Cells

' 8olarity" 9asal 8ole" :ucleus$ Grganelles3pical 8ole" )ecretory Aranules

' Location" %ucus'secreting cells" Aoblet Cells' intestinal ; respiratoryepithelium

%ucous 3cini' salivary glandsAastric Epithelium

ormone'secreting cells" 3denohyphysis

1+. Cells speciali"ed for lipid synthesis

' Location" Exocrine Cells ' )ebaceous gland

Endocrine Cells Leydig Cells' estis *ollicular Cells Gvary 3drenal Cortex Cells

1,. Cells speciali"ed for amines and small peptides synthesis

7 #igestive tract entero'endocrine cells


10/38

' )omatostatin +# Cells-' 1(8 +# Cells-' )erotonin +EC Cells-' Colecistochinin +( Cells-' A(8 +< Cells-

' %otilin +%o Cells-' :eorotensin +: Cells-' )ecretin +) Cells-

1. Cells speciali"ed for ions transport (serous cells)

4eabsorption" ' Jniferous tubules' Excretory ducts$ salivary glands' #igestive tract

)ecretion" ' Endothelial Cells' Ciliary processes

' Ependymal cells Choroid plexus

20. 5yoepithelial cell

Location )urrounding secretory portion of" )alivary glands$ lacrimal glands$sweat glands ; mammary glands

*eatures" ' Cyto6eratin laments' epithelial tissue' Contractile laments muscle tissue

' A38 >unctions' synchronizing' #esmosomes with epithelial cells' emidesmosomes with basement membrane

21. 5erocrine# apocrine# holocrine mechanisms of secretion4 e3amples

!erocrine secretion" Exocytosis of stored secretory granules

*pocrine secretion:secretion of product along with apical cytoplasm

Holocrine secretion:destruction of entire cell during secretion

CG::EC(1E ())JE22. Definition# basic structure and functions of connecti$e tissues.


11/38

#enition" tissue that connects$ supports$ binds or separates other tissuesor organs typically having relatively few cells embedded in an amorphousmatrix often with collagen or other bers.

*unctions" ')tructural support +capsules$ bone$ cartilage-

' :utrition' #efense +nonspecic ; immune-' Cell growth ; #i5erentiation' Cell migration' (nsulation

Characteristics"' common embryological origin 7 mesoderm' (nnervated ; 1ascularized +direct blood supply-K cartilage is only exception with no capillary beds K'EC matrix ' ground substance +gelatinous glycoproteins-

' structural bers +brous proteins eg" collagen$ elastin$reticulin-

ypes"'Connective issue 8roper ' loose

' dense +brous- irregular' dense +brous- regular

' )pecialized Connective issue" 'adipose tissue' reticular' elastic' cartilage +hyaline$ elastic$ brocartillage-

' bone' blood

2. !tructure and ultrastructure of connecti$e tissue fibers% colla*en#

elastic# reticular.

*ibers ' proteins that are embedded in the ground substance ' provide structural support$ adhesion$ connect cells

' Collagen ' tough provides high tensile strength

' also called white bers ' highly polymerized$ gigantic molecules ' tough$ moderate 2exibility ' bone$ cartilage$ tendons ligaments

'Elastic bers 7 Elastin ' branched smaller$ thinner bers thancollagen


12/38

' very 2exible ; elastic but also strong' can be stretched to HM of its original length' 3


13/38

' *ibril associated collagen" ypes (S ; S((' :etwor6'forming collagen" ype (1' 3nchoring collagen" ype 1((

2. 6round substance% molecular composition and functions

' participate sto binding cells to bers' colorless ; transparent in usual stains' %ay be solid$ 2uid or gel'Components" ' Cell 3dhesion 8roteins

- *ibronectin' binds cells$ collagen ; A3A=- Laminin mediates attachment of epithelial cells to

basal laminae

' 8roteioglycans large polysaccharide molecules bound toprotein core

' Alycosaminoglycans +A3As- linear polysaccharidescomposed of repetitive disaccharide units$ attached toproteoglycans

2+. Connecti$e tissue cells% classification

8roper to connective tissue +*ixed Cells-' *ibroblast' brocyte +condro' $ osteo' -' %yobroblast

' 3dipocyte +uni' $ multiocular-' 4eticular

%igrated' granulocytes' 9 ; lymphocytes' %acrophages' %ast cells' %elanocytes' 8lasma cell

Cells that produce/degrade the EC matrix' broblasts$ osteoblasts$ condroblasts$ macrophages

%etabolic Cells' adipocytes

#efense +)pecic/:on')pecic-


14/38

' lymphocytes$ macrophages$ neutrophils$ mast cells$ plasma cells

2,. Fibroblast-fibrocyte% structure# ultrastructure# functions

*ibroblast' %ost fre,uent cell

' L! Elongated cells$ =HTm$ branched processes$ basophilic cytoplasm$oval$ euchromatic nucleus$ or = nucleoli' TE! abundant 4E4 ; prominent Aolgi apparatus

8roduce"' Elements of EC %atrix" 8rocollagen$ proelastin$ brilin$ A3A$ 8roteoglycans; Alycoproteins' Enzymes" %atrix metalloproteinases ; Collagenase ; Elastase

' Arowth *actors

8roperties"' ability to switch its phenotype" *ibroblast *ibrocyte

' can change shape' mobile' induces di5erentiation of surrounding cells

+%yobroblasts 7 *ibroblasts that contain actin-

2. 7nilocular8white adipocyte% structure# ultrastructure# functions

' L!' round +when isolated- G4 polygonal in groups ' one large lipid droplet +inclusion-

' 3 thin rim of cytoplasm at the periphery that contains a 2attened$heterochromatic nucleus +Usignet ringV-

' TE! )mall Aolgi complex$ 4E4$ mitochondria ; microlaments

*unctions" secrete adipo6ines$ resistin$ adiponectin$ leptin ; apelin.

0. 5ultilocular8brown adipocyte% structure# ultrastructure# functions

' smaller than white adipocytes' %ostly found before birth and in neonates

L!' many small lipid droplets in cytoplasm foamy loo6


15/38

' round central nucleus TE! many mitochondira +high concentration of cytochromes in themitochondria is responsible for brown color of the aggregates of multiocularadipcytes brown color also due tohigh vascularization ! capilaries for each

brown adipocyte-

1. 9eticular cell% structure# ultrastructure# functions

*unctions' 8roduce reticular bers$ which form the ne structural networ6 of organssuch as the lymph nodes$ spleen and bone marrow.' )ynthesizes type ((( Collagen' hey also direct 9 cellsand cellsto specic regions within the lymphatictissue.

L! )tar'shaped cells with long and thin processes that establish anchoring>unctions with neighboring cells round$ central$ pale nucleus.

K)hould not be confused with the reticulocyte$ an immature erythrocyte

2. 5acropha*e% structure# ultrastructure# functions

#erived from peripheral blood monocytes$ (nvolved in phagocytosis andin2ammatory response' 3 family of cells with various shapes$ localizations and names"' istiocytes" connective tissue'


16/38

TE!' numerous lysosomes$ phagosomes and pseudopodia$ abundant 4E4$)E4$ mitochondria and Aolgi complex.

*unctions" %ain function" phagocytosis

' riggered by a specic interaction between membrane receptors andligands.

Conse,uences"Cell movement towards target particle8seudopodia formation engulfment4espiratory burst)ecretion" cyto6ines$ interferon$ complement & coagulation factors8roduction of matrix metalloproteinases

&&$ !ast cell: structure, ultrastructure, functions

)tructure

Large$ Gval cell$ =H'!H mm Cytoplasm has numerous basophilic$ metachromatic

granules

Jltrastructure

. %any granules

=. extensive Aolgi complex

!. cisternae of 4E4

D. free ribosomes$ mitochondria and numerous microvilli and folds.

. 4ich in istamine & eparin

*unctions

3 mobile macrophage cell of the connective tissue$ able to perform phagocytosis$

plays a ma>or immune role in allergies$ also involved in wound healing and defense

against pathogens.


17/38

+otes

1ery similar to basophil +both in function and appearance-$ it is located in most of

the loose connective tissue along blood vessels.

&$ Plasma cell: structure, ultrastructure, functions

)tructure

8ear/Gvoid shaped cells$ basophilic cytoplasm +due to abundant 4E4- with a

perinuclear pale area +Aolgi apparatus-$ can contain acidophilic 4ussel bodies

+secretory granules-

Eccentric and visible :ucleus$ with hetero and euchromatin in a Xcloc6faceX pattern

meaning theyYre assembled in a circular manner around the periphery of the

nucleus +much li6e numbers on the cloc6-

Jltrastructure

Extensive Aolgi complex$ abundant 4E4$ secretory granules +4ussel bodies-$ free

ribosomes & methachondria.

*unctions

%ainly secrete immunoglobulins +antibodies-" (g%$ (gA$ (g3$ (gE$ they originate in 9

lymphocytes that are terminally di5erentiated as a result of a response to anantigen challenge.

&-$ Classi.cation of connecti"e tissues

The classi.cation is based on the composition and organization of the

componants and its functions/

#$ Embryonic connecti"e tissue

%esenchye

%ucous connective tissue

%$ *dult connecti"e tissue

Loose connective tissue

#ense +brous- connective tissue


18/38

#ense regular connective tissue

#ense irregular connective tissue

4eticular connective tissue

Elastic connective tissue

&$ 0pecialized connecti"e tissue

3dipose tissue

Cartilage

9one

ematopoietic +bone marrow-

9lood

&1$ Loose connecti"e tissue: structure, localization

)tructure

Comprised of all the main componants of a connective tissue in e2ual

proportions, "ery di"erse in types of cells/ most numerous being

.broblasts 3 macrophages

3bundant ground substance$ collagen$ elastic and reticular bers$ very 2exible andvery well vascularized$ and relativly delicate.

Localization

)upports epithelial tissues

Ensheathes the lymphatic and blood vessels

8apillary layer of the dermis

he serosal linings of peritoneal and pleaural cavities

Alands and mucous membranes

&4$ 5ense irregular connecti"e tissue: structure, localization

)tructure


19/38

*ew cells +compared to loose C-$ mainly brocytes +occasional mast cells &

macrophages-

Clear predominance of collagen bers

*ew ground substance

Less 2exible thus more resistant to stress

The collagen .bers are bundled 67TH +O 5E87+7TE O97E+T*T7O+ hence

labelled irregular;

hree deminsional networ6 B 4esistant to stress from all angles

Localization

Capsules of the parenchimatose organs

#ermis

)ubmucosa of the digestive tract

8eriosteum

8erichondrium

&


20/38

)econdary 9undles of endotenonium loose connective tissue with blood

vessels and nerves ' Peritenonium

External sheath of dense connective tissue ' epitenonium

Localization

9etween striated muscle and bone

&>$ *poneuroses: structure, localization

)tructure

inextensible structure that attaches striated muscle to bone +or other muscles-

hic6 and predominant collagen bers

%ultiple layers"

8arallel in the same layer

perpendicular on the collagen bers from the layers above and beneath

+textile aspect-

*ibrocytes ' *lattened$ narrow shaped

+ote the fastest and easiest (ay to identify on a slide is to pay

attention to the textile orginization of the collagen .bers

Localization

9etween muscle and bones +and sometimes between muscles and other muscles or

structures$ basically attaches the epiphysis of the bone to other structures-

?$ 9eticular connecti"e tissue: structure, localization

)tructure

)pecialized loose connective tissue$ double mesh(or=" 9eticular cells 3 a

net(or= of branched reticular .bers, reticular bers are enveloped by the

cytoplasm of reticular cells the bers however are ES43CELLJL34 being

seperated from the cytoplasm by the cell membrane


21/38

Localization

*ramewor6 of the bone marrow and lymphoid tissue +lymph nodes$ spleen-$

supports the soft organs in the periphery.

#$ Elastic tissue: structure, localization

)tructure

Predominance of parallel thic= elastic .bers +remember orcein & furschin

stain- and bet(een them rare collagen .bers and @attened .broblasts

Localization

yellow ligaments of the spinal chord

)uspensory ligaments of the penis

*unction ' 8rovide elasticity

%$ !ucous tissue: structure, localization

*n embryonic connecti"e tissue

)tructure

Aelatin'li6e extracellular matrix +very loose-

*bundanceof amorphous ground substance +also 6now there as

whartonYs >elly-

Thin collagen .bers

0pindleshaped cells +mesenchymal cells-

Localization

Ambilical chord

&$ 6hite adipose tissue: structure, localization


22/38

)tructure

8at cells 3 thin layers of loose irregularconnecti"e tissue

Jnilocular +have only one cavity-/white adipocytes '

round +when isolated- or polygonal in groups

cytoplasm ' a thin rim at the periphery Gne large lipid droplet +inclusion-

nucleus ' 2attened$ heterochromatic Xsignet ringV and compressed onto the cell

membrane by the lipid droplet.

Zhite to dar6 yellow due to carotenoids +organic pigments-

)mall amounts of collagen$ elastic bers and ground substance

Localization

hroughout the human body$ distribution is regulated endocrinologically according

to gender and age.

$ 6hite adipose tissue: function

%ainly store energy$ insulate and cushioning of vital organs.

Energy storage '

3dipocytes are specialized for synthesis$ storage$ and mobilization of neutral fats+triglycerides-. ormones$ such as insulin$ and the sympathetic nervous system$

which innervates adipose tissue$ control these activities. hese fats are stored in

nonmembrane'bound lipid droplets. Zhen fats are needed to provide fuel for cells

in other tissues$ adipocytes release them as fatty acids into circulation. #ietary

lipids from the intestine also circulate in blood as water'soluble lipoproteins called

chylomicrons. ogether with very'low'density lipoproteins +1L#Ls- from the liver$

they reach the adipocyte surface via capillaries. Lipoprotein lipase$ an enzyme

produced by adipocytes$ releases fatty acids and monoglycerides from chylomicrons

and 1L#Ls that are then moved to the adipocyte cytoplasm. 4e'esterication into

triglycerides occurs in the smooth endoplasmic reticulum$ followed by storage in

lipid droplets. )ome fatty acids are also produced from glycogen in adipocytes.

)cattered mitochondria$ a small Aolgi complex$ and cytos6eletal laments are other

organelles in the cytoplasm. 3dipocytes also secrete steroid hormones$ cyto6ines$

and leptin$ a peptide hormone$ which functions in appetite regulation by acting on

the hypothalamus.


23/38

-$ Bro(n adipose tissue: structure, localization

)tructure

8redominance of brown adipocytes

Zell vascularized

Bro(n adipocyte

%ultilocular$ polygonal and smaller comapred to white adipocytes

)pherical$ central nucleus

Cytoblasm"

Areat nuber of lipid dropletsthat "ary in size

+umerous mitochondria with abundant long cristae

Epithelial'li6e arrangment where the cells are closely pac6ed in masses and

assosiated with blood capillaries.

)ubdevided by connective tissie into lobules$ better delineated +compared to

unilocular adipose tissue-

Cells recie"e direct sympathetic inner"ation

Localization

Large amounts in newborn

)carce at the adult

(n the cervical and mediastinum region +except perirenal & periaortic-

1$ Bro(n adipose tissue: function

hermogenetic activity

eat production$ and the recruitment process in the tissue +that results in a higher

thermogenic capacity- are under the control of norepinephrine released from

sympathetic nerves. (n thermoregulatory thermogenesis$ brown adipose tissue is


24/38

essential for classical nonshivering thermogenesis +this phenomenon does not exist

in the absence of functional brown adipose tissue-$ as well as for the cold

acclimation'recruited norepinephrine'induced thermogenesis. eat production from

brown adipose tissue is activated whenever the organism is in need of extra heat$

e.g.$ postnatally$ during entry into a febrile state$ and during arousal from

hibernation$ and the rate of thermogenesis is centrally controlled via a pathwayinitiated in the hypothalamus. *eeding as such also results in activation of brown

adipose tissue a series of diets$ apparently all characterized by being low in

protein$ result in a leptin'dependent recruitment of the tissue this

metaboloregulatory thermogenesis is also under hypothalamic control. Zhen the

tissue is active$ high amounts of lipids and glucose are combusted in the tissue. he

development of brown adipose tissue with its characteristic protein$ uncoupling

protein' +JC8-$ was probably determinative for the evolutionary success of

mammals$ as its thermogenesis enhances neonatal survival and allows for active

life even in cold surroundings.

4$ Hyaline Cartilage: structure, localization

)tructure

CELLAL*9 CO!P*9T!E+T:

0 Chondroblasts

0 Chondrocyte

*ound in matrix cavities 'lacunae

*rranged in isogenous groups clusters or columns;

0 8erichondrium cells

!*T97

0 erritorial matrix

0 interterritorial matrix

Components"

. *ibers" collagen ((.

=. Around substance

Localization


25/38

(n the fetus '

8orming the s=eleton

(n adults '

+ose, Larynx, Trachea, Bronchus, Dentral end of ribs, *rticular surface ofsome bones 3 in gro(th cartilage of long bones


26/38

*ppearance under microscope:


27/38

H. Chondroblast$ and chondrocyte" structure$ ultrastructure$ localization

5e.nition:

Chondroblast" (mmature chondrocyte

' #ivide

' )hape" elliptical long axis parallel to the surface of the cartilage

' 3lso secretes antiangiogenesis factor a substance that prevents blood vessel

growth-

3nti7 against$ angio7 vessel$ genesis 7 production 7B antiangiogenesis.

Chondrocyte" %ature cell of the cartilage

' #o not divide

' )hape" round

Chondrocytes are distributed either singularly or in clusters called isogenous

groups

Zhen the chondrocytes are present in isogenous groups$ they represent cells that

have recently divided. 3s the newly divided chondrocytes produce the matrix

material that surrounds them$ they are dispersed

Cell type 0tructure Altrastructure LocalizationChondroblast +uclei:

4ound andbasophilicEuchromatic+active-'= nucleiCytoplasm:9asophilic

uxtanuclear pale

4E4$ Aolgi$

%itochondria$glycogen$ lipiddroplets allpresent%any shortcytoplasmicpro>ections

Cells are

isolatedlocated attheperipheryunder theperichondrium

K*ound in lacunae


28/38

region 3*E4 theysecrete matrixtherefore mostperipheralchondroblastsaren@t in lacunae

Chondrocyte +uclei:4ound andbasophilicCytoplasm:3cidophilic

*ew organelles(ncreased"

Alycogen

Lipid

droplets#ecreased"

)ynthesis

Cells form

groupscentrally.

KCompletely lllacunae

9oth secrete all components of the matrix +bres and ground substance-

. Aeneral structure of osseous tissue.

5e.nition:

Bone is a specialized form of connective tissue that$ li6e other connective tissues$

consists of"

Cells +osteoblasts and osteocytes-

Extracellular matrix-.

Grganic matter +osteoid-" amorphous ground substance and collagen bres

(norganic matter +minerals-

he feature that distinguishes bone from other connective tissues is the

mineralization of its matrix$ which produces an extremely hard tissue capable of

providing support andprotection.

he mineral is calcium phosphate in the form of hydroxyapatite crystals


29/38

*orms of bone"

. %icroscopic

*orm of bone Aeneral description8rimary +immature$ woven- 7rregulararray of collagen bres

igher proportion of osteocytesLower mineral content

)econdary +mature$ lamellar- 9egular bands of collagen bresarranged in sheets +lamellae-

=. %acrocopic

*orm of bone #escriptionCompact +#ense- bone C.9 3 compact$ dense layer forming

the outside of the bone.

Cancellous +spongy- bone ).9 a sponge'li6e meshwor6 consistingof trabeculae +thin$anastomosing spicules of bonetissue- forming the interior of thebone

he spaces within the meshwor6are continuous and$ in a livingbone$ are occupied by marrow andblood vessels

=. Gsteoblast$ osteocyte$ osteoclast" structure$ ultrastructure$ functions

9one cell )tructure Jltrastructure

Localization

*unctions

Gsteoblast 0hape" columnar$cuboidal +matrixsynthesis-$ 2attened+inactive-+ucleus:8ale staining%ultipleCytoplasm:9asophilicCytoplasmicprocesses7Bcontact withneighbouring cells

4E4$ Aolgi$%itochondria

Liningbone+endosteum$periosteum$trabeculae$metaphysis- (.esites ofbonewhereremodelling is notoccurring

:G celldivision)ynthesizethe organiccomponents of matrix

Gsteocyte 0hape: 4educed Located Gsteocytes


30/38

*lattenedElongated+ucleus:*lattenedCondensed chromatinCytoplasm:

Less basophilic andmore acidophilicLO+, thincytoplasmicprocessesFGentermatrix canaliculi 7Bad>acent cells ma6econtact via gap

>unctions

organelles betweenlayers ofosteon+ concentricarrangement of

bonetissuearoundbloodvessels-andoccupylacunae

cansynthesizenew matrix

Gsteoclast Large%ulti'nucleatedCytoplasm:acidophilic

:umerouslysosomes

*ound atsiteswherebone isremoved

4esponsiblefor bone

resorption

!. (ntramembranous ossication

+di5erence with endochodral ossication-

http"//answers.yahoo.com/,uestion/index[,id7=HHQ=H=!=D33EGsLJ

5e.nition: (n intramembranous ossication bone is formed by di5erentiation of

mesenchymal cellsinto osteoblasts.

*or 2at bones

)ome of the pale'staining$ elongated mesenchymal cells within the

mesenchyme migrate and aggregate in specic areas$ the sites where bone is

destined to form. his condensation of cells (ithin the mesenchymal

tissueinitiates the process of intramembranous ossication.

0tages:

. Aroup of mesenchymal cells di5erentiate \osteoblasts secrete matrix which

then becomes mineralized=. \(slands of developing bone +)8(CJLE)-!. *usion of )picules \ 439ECJL3E in C3:CELLGJ) +spongy- boneD. \ Arowth and fusion of trabeculae \ CG%83C bone

D. Endochondral bone formation

5e.nition: %esenchymal cells di5erentiate into chondroblasts that$ in turn$

produce cartilage matrix.
http://answers.yahoo.com/question/index?qid=20081211025324AAEOsLUhttp://answers.yahoo.com/question/index?qid=20081211025324AAEOsLU


31/38

*or long bones

7nitially, a hyaline cartilage model (ith the general shape of the

bone is formed$

8rocess begins with the proliferation and aggregation of mesenchymal cells

at the site of the future bone

)tages"

he process begins with the formation of a cartilage model

#- 3 periosteal +perichondrial- collar of bone forms around the diaphysis +shaft- of

the cartilage model

+%- then$ the cartilaginous matrix in the shaft begins to calcify


32/38

+&-. 9lood vessels and connective tissue cells then erode and invade the calcied

cartilage

+-$ creating a primitive marrow cavity in which remnant spicules of calcied

cartilage remain at the two ends of the cavity. 3s a primary center of ossication

develops$ the endochondral bone is formed on spicules of calcied cartilage. hebone at the ends of the developing marrow cavity constitutes the metaphysis.

8eriosteal bone continues to form

+-- the periosteal bone is formed as the result of intramembranous ossication.

9lood vessels and perivascular cells invade the proximal epiphyseal cartilage

+1-$ and a secondary center of ossication is establishedin the proximal epiphysis

+4-. 3 similar epiphyseal +secondary- ossication center forms at the distal end of

the bone

+-$ and nally$ with cessation of growth$ the proximal epiphyseal cartilage

disappears

+#?-. he metaphysis then becomes continuous with the epiphysis. Epiphyseal lines

remain where the epiphyseal plate last existed.

. Composition of plasma

F. Erythrocytes


33/38

5e.nition:a6a red blood cells

Pathology:

cytopenia 7 lower than normal +associated with anemia-$

cytosis 7 higher than normal +e.g.polycythemia vera-

0ize:

' ]P. ^m diameter fresh

' P.= ' P.D in stained smears

'H$Q =$F ^m thic6

Constant diameter allows 49Cs to be used as a

scale to compare with other cells"

0macrocytes B R ^m$

0microcytes _ F ^m

0anisocytosis 7 variation in size

)tructure Jltrastructure *unction9iconcave disc

folding increases

surface area +!HMmore surface area-

composition of

plasma membranegives 2exibility+s,ueeze throughcapillaries-

RPM hemoglobin

:o nucleus:o centrioles

:o organelles:o mitochondria

no cell division +as

a result of no

centrioles$ nucleior organelles- no mitochondria

means they cangenerate 38anaerobically 7Bpreventsconsumption of theG=that theytransport

ransport G=


34/38

P. #i5erential count of blood leu6ocytes

*im: helps to indicate what type of disease may be present in a patient

!ethod:

. Gbtain sample of venous blood from patient=. 8lace one drop of blood on to slide!. 8repare a smearD. Jsing light microscopy$ count HH blood cells$ noting each leu6ocyte type and

their fre,uency.

+ormal 2uantities in blood:

:eutrophils 7 DQ'FFM

Eosinophils 7 'DM

9asophils" H'H.M

%onocytes 7 QM

Lymphocytes 7 ='=PM

Pathological results and indications:

(ncrease in"

:eutrophils" acute bacterial in2ammation

Eosinophils" allergic reaction$ parasitic infection$ chronic in2ammation

9asophils" allergic reaction therefore basophils release histamine

Lymphocytes" in viral infections and tumour cells

Q. :eutrophil" structure$ ultrastructure and functions

5e.nition:

)tructure Jltrastructure *unctionsLarger than 49C

#iameter 7 H'=

micrometresPolymorphonuclear:

:ucleus has

multiple lobes

+ucleus:as heterochromatin atthe periphery andeuchromatin morecentrally0mall golgi apparatus

:eutrophils are activephagocytes that utilize avariety ofsurface receptors torecognize bacteria andother infectious


35/38

connected bychromatin

Cytoplasm:

Contains speci.c

granules 7B cell isranulocyte

Aranules have

a`nity for 9othbasic and eosindyes.

8e( other organelleslycogen particlesranules:

)pecic granules

+primary-

3zurophilicgranules+secondary$ non'specic lysosomes-

ertiary granules

agents at the site ofin2ammation.

R. 9asophil" structure$ ultrastructure and functions

)tructure Jltrastructure *unctionshe same size as

neutrophils+ucleus:3lsopolymorphonuclear"usually bi'lobed or tri'lobed.Cytoplasm:amed basophil becausethe numerous largegranulesin theircytoplasm stain withbasic dyes 7B blue

appearance herefore granules

cover 9Gnucleus andCytoplasm

+uclues:

eterochromatin alsolocated at the peripheryand euchromatincentrallyranules:' )pecic +basophilic-' 3zurophilic +non speciclysosomes found in allleu6ocytes-

9asophils bind an

antibody7gE$ through high'a`nity*c receptors expressedon their cell surface. hesubse,uent exposure to$and reactionwith$ the antigen+allergen- specic for (gEtriggers the activation ofbasophils and the releaseof "asoacti"e agentsfrom cell granules.

FH. Eosinophil" structure$ ultrastructure and functions

)tructure Jltrastructure *unctions3bout the same size asneutrophils+uclues:9asophilicPolymorphonuclear:nucleus is typically bi'

+ucleus:3s in neutrophils$ thecompact heterochromatinof eosinophils is ad>acentto the nuclear envelope$whereas the euchromatin

Eosinophils areassociated with allergicreactions$ parasiticinfections$ and chronicin2ammation.


36/38

lobedCytoplasm:Contains largeacidophilic granuleswhich cover thecytoplasm7B cannot see

whether the cytoplasm isacidophilic or basophilic

is located in the centre ofthe nucleus.8e( organellesranules:

)pecic +large

eosinophilic-

3zurophilic +non

specic lysosomes-

F. %onocyte" structure$ ultrastructure and functions

)tructure Jltrastructure *unctionsLargest of all theleu6ocytes"

#iameter" Q

micrometres+ucleus:

ypically more indentedthan other leu6ocytes 7B6idney shaped

appearance9asophilic*granulocyte nucleusis non'segmented so cellis described asmononuclearCytoplasm:9asophilic/azurophilic

Organelles:

Aolgi apparatus

and centrioles arelocated in the?indented@ areaaround the nucleus

4E4$ )E4 and

small mitochondriaranules:

3zurophilic

granules+lysosomescontained in allleu6ocytes-

#uring in2ammation$ themonocyte leaves theblood vessel at the site ofin2ammation$transforms into atissue macrophage$andphagocytosesbacteria$other cells$ and tissue

debris. 4emain in the

blood for onlyabout ! days.

F=. Lymphocyte" structure$ ultrastructure and functions

)tructure Jltrastructure *unctionshree groups oflymphocytes can beidentiedaccording to size" small$medium$ and largelymphocytes$ rangingin diameter from F to !H

Organelles:

Aolgi$ ribosomes$

mitochondria allvary in amountaccording to sizeof lymphocyte

7mmunocompetentcells +i.e.$ cells that havedevelopedthe capacity to recognizeand respond to antigensand arein transit from one


37/38

micrometres+ucleus:

4ound

!ononuclear

+non'segmented-

9asophilic

Large and occupies

most of the cellCytoplasm

3ppears as a

small$ blue ringaround nucleus+contains onlyazurophilicgranules

4ibosomes 7B

blue appearancedue to slightbasophilia

ranules:

3zurophilic

lymphatic tissue toanother-

8unctionally diIerentlymphocytes:T cells have a long life

span and are involved incell mediatedimmunity.) B cells have variablelife spans and areinvolved in theproduction of circulatingantibodies.) +J cells areprogrammed during theirdevelopment to6ill certain virus'infected

cells and some types oftumorcells.

hey also secrete

an antiviral agent$interferon

F!. 8latelet" structure$ ultrastructure and functions

)tructure Jltrastructure *unctions0mallcytoplasmicfragments derived frommega6aryocytes.

='! micrometres in

diameter!embranebounded

*nucleate

)tructural organization ofthe thrombocytecytoplasm categorizedinto four zones

he peripheral zoneconsists of the cellmembranecovered by a thic6surface coat ofglycocalyx.

' he integralmembraneglycoproteinsfunction asreceptors in

Continuous surveillanceof blood vessels$9lood clot formation$4epair of in>ured tissue.


38/38

platelet function.he structural zonecomprises microtubules$actin laments$ myosin$and actin'bindingproteins that form a

:etwor6 supporting theplasma membrane.

' responsible formaintaining theplatelet@s discshape.

he organelle zoneoccupies the center ofthe platelet. (tconsists of mitochondria$peroxisomes$ glycogenparticles$

and at least three typesof granules dispersedwithin thecytoplasm.

he membrane zone

Documents

Histo Topic List Final Version