The Cell Histology

8/3/2019 The Cell Histology

http://slidepdf.com/reader/full/the-cell-histology 1/60

The CellThe Cell



Example of a cell – graafian follicleExample of a cell – graafian follicle



Example of a cell – ovarian follicleExample of a cell – ovarian follicle



Example of Hair cells of the EarExample of Hair cells of the Ear



Components of the BodyComponents of the Body1.1. Cell = each cell is a discrete entity, bound by aCell = each cell is a discrete entity, bound by amembrane that “Isolates” it from itsmembrane that “Isolates” it from its

environment.environment.

2.2. Intercellular or Extracellular substances =Intercellular or Extracellular substances =

materials that lie between cells to support andmaterials that lie between cells to support andnourish them.nourish them.

3.3. Body Fluids = includes the following:Body Fluids = includes the following:

a. Blood = confined within the vascular systema. Blood = confined within the vascular system

b. Tissue or intercellular fluid = between & b. Tissue or intercellular fluid = between & around the cellaround the cell

c. Lymph = drain tissue fluid back to thec. Lymph = drain tissue fluid back to thevenous systemvenous system



Typical animal cellTypical animal cell



Phagocytosis & PinocytosisPhagocytosis & Pinocytosis



2 Types of Cells2 Types of Cells1.1. Prokaryotic =(Prokaryotic =(greek greek pro before + Karyon,pro before + Karyon, nucleus)nucleus)

Found in Primitive cells such as bacteria.Found in Primitive cells such as bacteria.

Metabolic & hereditary components are mixed.Metabolic & hereditary components are mixed.

Have no histones (specific basic proteins)Have no histones (specific basic proteins)bound to their DNA.bound to their DNA.

No Membranous organelles.No Membranous organelles.

2. Eukaryotic = in all higher plants and animals.2. Eukaryotic = in all higher plants and animals.

Bulk of hereditary material is isolated in aBulk of hereditary material is isolated in a

membrane bound nucleus lying in themembrane bound nucleus lying in the

remainder of the cell or Cytoplasm.remainder of the cell or Cytoplasm.



Typical animal cellTypical animal cell



The Cell membraneThe Cell membrane



Job of the cell membraneJob of the cell membrane

Transport by:Transport by:

Diffusion =Diffusion = from high to lower concentrationfrom high to lower concentration

Facilitated Diffusion =Facilitated Diffusion = use protein channelsuse protein channels

Active transport = Active transport = use energyuse energy

Phagocytosis & Pinocytosis =Phagocytosis & Pinocytosis = taking on too bigtaking on too big

molecules.molecules. Immune systemImmune system

Cell junctionsCell junctions



Cell skeleton with cytosol removedCell skeleton with cytosol removed



Cell membraneCell membrane

It is a 2 lipid layer of Phospholipids.It is a 2 lipid layer of Phospholipids.

Lipids ,Lipids , the water fearing (hydrophobic)the water fearing (hydrophobic)

Phosphoate,Phosphoate, the water loving part ( Hydrophilic)the water loving part ( Hydrophilic)

the barrier that kept the contents intact.the barrier that kept the contents intact.

Serves a s a gateway & helps in theServes a s a gateway & helps in the

control of passage of materials in & out.control of passage of materials in & out.



ProtoplasmProtoplasm

Living substance of the cell subdivided into 2Living substance of the cell subdivided into 2compartments.compartments.

Cytoplasm = extending from the PlasmaCytoplasm = extending from the Plasmamembrane to the Nuclear envelope.membrane to the Nuclear envelope.

Karyoplasm = the substance forming theKaryoplasm = the substance forming thecontents of the nucleus.contents of the nucleus.

Exists in a colloidal state cannot be filteredExists in a colloidal state cannot be filteredthrough Natural membranes.through Natural membranes.

Components:Components:

Protein , Nucleic acids, Carbohydrates, Lipids,Protein , Nucleic acids, Carbohydrates, Lipids,

Inorganic materials, Water.Inorganic materials, Water.



Components of the ProtoplasmComponents of the Protoplasm

1.1.

Protein = main structural elements of the cellProtein = main structural elements of the cell

and the Intercellular material. Exists as:and the Intercellular material. Exists as:

Pure protein, Lipo protein, Glycoprotein,Pure protein, Lipo protein, Glycoprotein,

Proctoglycans or Mucoproteins.Proctoglycans or Mucoproteins.

E.G. secretory products such as enzymes orE.G. secretory products such as enzymes orsome hormones.some hormones.

2. Nucleic acids = DNA, found mainly in the2. Nucleic acids = DNA, found mainly in the

Nucleus. RNA, found in Nucleus & cytoplasmNucleus. RNA, found in Nucleus & cytoplasm3.3. Carbohydrates =Carbohydrates = as glucose stored as Glycogenas glucose stored as Glycogen

4.4. Lipids = also an energy source. ImportantLipids = also an energy source. Important

component of cellular membrane.component of cellular membrane.



5. Inorganic materials = exists as Free radicals,5. Inorganic materials = exists as Free radicals,

combined with Proteins & Lipids.combined with Proteins & Lipids.

* involved in Essential functions.* involved in Essential functions.a. Maintenance of Osmotic pressure gradients.a. Maintenance of Osmotic pressure gradients.

b. Muscle contraction/ Relaxation.b. Muscle contraction/ Relaxation.

c. Tissue rigidity, e.g. bone.c. Tissue rigidity, e.g. bone.d. Cell adhesiond. Cell adhesion

e. Enzyme activatione. Enzyme activation

6.6. WaterWater* 75% of Protoplasm* 75% of Protoplasm

* Partly Free, available for Metabolic Processes.* Partly Free, available for Metabolic Processes.

* Partly bound to protein as a structural component.* Partly bound to protein as a structural component.



Properties of ProtoplasmProperties of Protoplasm

IrritabilityIrritability ConductivityConductivity

ContractilityContractility RespirationRespiration Absorption Absorption

SecretionSecretion ExcretionExcretion GrowthGrowth



Irritability = capacity to respond to a stimulus.Irritability = capacity to respond to a stimulus. Conductivity = can transmit a wave of excitationConductivity = can transmit a wave of excitation

(an electrical impulse) through out the cell from(an electrical impulse) through out the cell fromthe point of stimulus. Highly developed in Nervethe point of stimulus. Highly developed in Nervecells and to a lesser extent in Muscle cells.cells and to a lesser extent in Muscle cells.

Contractility = property of changing shape in theContractility = property of changing shape in the

sense of shortening, e.g. Muscle cells.sense of shortening, e.g. Muscle cells. Respiration = Essential for life. A processRespiration = Essential for life. A process

whereby food substances & Oxygen within thewhereby food substances & Oxygen within thecell interact chemically to produce Energy,cell interact chemically to produce Energy,

Carbon dioxide and water.Carbon dioxide and water. Absorption = imbibition of materials that later Absorption = imbibition of materials that later

maybe assimilated by the cell in metabolism ormaybe assimilated by the cell in metabolism orotherwise utilized.otherwise utilized.



Secretion = process by which cell extrudesSecretion = process by which cell extrudes

material (useful) such as Digestive enzyme or amaterial (useful) such as Digestive enzyme or a

Hormone.Hormone. Excretion = extrusion of waste material from theExcretion = extrusion of waste material from the

cell.cell.

Growth = increase in size resulting fromGrowth = increase in size resulting from increaseincrease in the amount of protoplasmin the amount of protoplasm BeyondBeyond

maximum sizemaximum size Increase in cell numberIncrease in cell number CellCell

divisiondivisionMetabolism.Metabolism.



MetabolismMetabolism

Chemically process by which nutrition isChemically process by which nutrition is

effected:effected:

> Breakdown of Protoplasm> Breakdown of Protoplasm

> Materials brought to the cell as food supply> Materials brought to the cell as food supply..

Catabolism = energy is released by CellCatabolism = energy is released by Cell

Anabolism = energy is utilized by cell to Anabolism = energy is utilized by cell to

produce materials that are retained orproduce materials that are retained or

released.released.



Components of the CellComponents of the Cell

Cytoplasm, 3 main structural components:Cytoplasm, 3 main structural components:

Organelles, Inclusions, CytoskeletonOrganelles, Inclusions, Cytoskeleton

Nucleus, includes:Nucleus, includes:Nuclear envelopeNuclear envelope

NucleolusNucleolus

NucleoplasmNucleoplasmChromatinChromatin



CytoplasmCytoplasm 3 main structural components:3 main structural components:

OrganellesOrganelles

InclusionsInclusions

CytoskeletonCytoskeleton Fluid component = CytosolFluid component = Cytosol Exhibits functional interactions among organelles. ResultExhibits functional interactions among organelles. Result

in:in: Protein synthesisProtein synthesis Intracellular digestion.Intracellular digestion.

Uptake & release of materialUptake & release of materialOrganelles = metabolically active units of living matter.Organelles = metabolically active units of living matter.

Limited by a membraneLimited by a membrane



CytoplasmCytoplasm

Organelles, composed of:Organelles, composed of: Plasma membrane, Ribosomes, Rough EndoplasmicPlasma membrane, Ribosomes, Rough Endoplasmic

Reticulum, Smooth Endoplasmic Reticulum, AnnulateReticulum, Smooth Endoplasmic Reticulum, Annulate

Lamellae, Mitochondria, Golgi complex(appartus), CoatedLamellae, Mitochondria, Golgi complex(appartus), Coated

vesicles, Lysosomes, Peroxisomes, Centrioles.vesicles, Lysosomes, Peroxisomes, Centrioles. Inclusions = Glycogen, Lipid droplets, LipofuscinInclusions = Glycogen, Lipid droplets, Lipofuscin

Cytoskeleton = Microtubules, Microfilaments,Cytoskeleton = Microtubules, Microfilaments,

Intermediate Filaments, Microtrabeculare lattice.Intermediate Filaments, Microtrabeculare lattice.



CytoplasmCytoplasmOrganellesOrganelles1.1. Plasma membrane = 7.5 nm thick Plasma membrane = 7.5 nm thick

>>Composed of a lipid bilayer and associated proteins.Composed of a lipid bilayer and associated proteins.

>Envelops the cells, aids in maintaining its structural & >Envelops the cells, aids in maintaining its structural &

functional integrityfunctional integrity

>Functions as a semipermeable membrane between>Functions as a semipermeable membrane between

the Cytoplasm and the External environment.the Cytoplasm and the External environment.

>Sensory device, recognize other cells & >Sensory device, recognize other cells & macromolecules.macromolecules.

>composed of an Inner leaflet (face cytoplasm), & >composed of an Inner leaflet (face cytoplasm), &

Outer leaflet( facing the extracellular environment)Outer leaflet( facing the extracellular environment)

>Exhibits a Trilaminar structure (the Unit membrane).>Exhibits a Trilaminar structure (the Unit membrane).



Plasma membranePlasma membrane

Lipid BilayerLipid Bilayer

Freely permeable to small nonpolar Lipid-solubleFreely permeable to small nonpolar Lipid-soluble

molecules but is impermeable to charged Ions.molecules but is impermeable to charged Ions.

Composed of Phospholipids, Glycolipids & Cholesterol.Composed of Phospholipids, Glycolipids & Cholesterol.

Phospholipids, are amphiphatic, possess a polar headPhospholipids, are amphiphatic, possess a polar head

(hydropholic) and two non polar (hydrophobic) fatty acyl(hydropholic) and two non polar (hydrophobic) fatty acyl

tails.tails.

The polar head faces the membrane surface.The polar head faces the membrane surface.

Double hydrophobic tail projects into the interior of theDouble hydrophobic tail projects into the interior of the

membrane.membrane.



Lipid LayerLipid Layer

Glycolipids = present in the outer leafletGlycolipids = present in the outer leafletonly.only.

Have a polar carbohydrates residue,Have a polar carbohydrates residue,extendds from the outer leaflet into theextendds from the outer leaflet into theextracellualr space. Forming part of theextracellualr space. Forming part of theGlycocalyx.Glycocalyx.

Cholesterol = located in both leaflets, 2%Cholesterol = located in both leaflets, 2%of Plasmalemma lipids, assists inof Plasmalemma lipids, assists inmaintaining the structural integrity.maintaining the structural integrity.



RibosomesRibosomes 12 nm wide and 25 nm long.12 nm wide and 25 nm long.

Consists of a small and large subunit composedConsists of a small and large subunit composed

of several types of nRNA. Maybe free in theof several types of nRNA. Maybe free in the

Cytosol, bound to membranes of the RER andCytosol, bound to membranes of the RER andOuter Nuclear membrane.Outer Nuclear membrane.

Are the sites where mRNA is translated into Are the sites where mRNA is translated into

Protein.Protein.

Ribosome composition:Ribosome composition:SubunitSubunit rRNA typerRNA type Number of Proteins.Number of Proteins.

Large (60S)Large (60S) (5S) (5.8S) (28S)(5S) (5.8S) (28S) 4949

Samll (40S)Samll (40S) 18 S18 S 3333



Rough Endoplasmic ReticulumRough Endoplasmic Reticulum

(RER)(RER) Site where noncytosolic proteins areSite where noncytosolic proteins aresynthesized;synthesized; Secretory, Plasma membrane, Lysosomal.Secretory, Plasma membrane, Lysosomal.

System of sacs or cavities,System of sacs or cavities, bounded by membranesbounded by membranes

outer surface – studded with ribosomesouter surface – studded with ribosomesinterior region – called cisternainterior region – called cisterna Has a membrane continuous with the Outer NuclearHas a membrane continuous with the Outer Nuclear

membrane ( perinuclear cisternae in continuity withmembrane ( perinuclear cisternae in continuity withCisternae or RER>Cisternae or RER>

Abundant in cells synthesizing secretory proteins = RER in Abundant in cells synthesizing secretory proteins = RER inparallel rays.parallel rays.

Has receptors (Ribophorins) in its membrane to which theHas receptors (Ribophorins) in its membrane to which theLarge Ribosomal subunit binds.Large Ribosomal subunit binds.



Smoothe Endoplasmic RetinaculumSmoothe Endoplasmic Retinaculum

Irregular network of membrane Bounded Channels thatIrregular network of membrane Bounded Channels thatlack Ribosomes on its surface, appearing smooth.lack Ribosomes on its surface, appearing smooth.

Appears as branching anastomosing tubules or vesicles, Appears as branching anastomosing tubules or vesicles,

membrane do not contain Ribophorins.membrane do not contain Ribophorins. Less common than RER Less common than RER Predominantes in Cells synthesizing steroids, TriglyceridesPredominantes in Cells synthesizing steroids, Triglycerides

& Cholesterols.& Cholesterols.

Serves different functions in different cell types:Serves different functions in different cell types:Steroid Hormone synthesisSteroid Hormone synthesis

Drug detoxificationDrug detoxification

Muscle contraction and relaxationMuscle contraction and relaxation



ER ( endoplasmic reticulum )R ( endoplasmic reticulum )

The endoplasmicThe endoplasmic

reticulum or ER is likereticulum or ER is like

a maze of membranea maze of membrane

canals runningcanals runningthroughout cells. It isthroughout cells. It is

closely related toclosely related to

several otherseveral other

membrane boundmembrane boundorganelles in the cellorganelles in the cell



Annulate Lamellae Annulate Lamellae

Parallel stacks of membranes (6-10) located nearParallel stacks of membranes (6-10) located nearthe nucleus.the nucleus.

Resembles the Nuclear envelope, including itsResembles the Nuclear envelope, including itsPore complexes.Pore complexes.

Often arranged with their Annuli (pores) inOften arranged with their Annuli (pores) inregister. Are continuous with the RER register. Are continuous with the RER

Are found in rapidly growing cells. Are found in rapidly growing cells.Germ cellsGerm cells

Embryonic cellsEmbryonic cells

Tumor cellsTumor cells



MitochondriaMitochondria Rod-shaped organelles [0,2um (width), 78 um (length)]Rod-shaped organelles [0,2um (width), 78 um (length)] Possess an outer membrane, which invaginates to formPossess an outer membrane, which invaginates to form

CristaeCristae Important in energy metabolism as major source of Important in energy metabolism as major source of

Adenosine Triphosphate (ATP). Adenosine Triphosphate (ATP). Site of many metabolic reactionSite of many metabolic reaction

Subdivided into an Intermediate compartment and anSubdivided into an Intermediate compartment and anInner compartment.Inner compartment.

Contains granules within the Matrix that binds theContains granules within the Matrix that binds theDivalent Cations Mg+2 & Ca+2Divalent Cations Mg+2 & Ca+2

Contains all of the enzymes of the Krebs (TCA) cycle.Contains all of the enzymes of the Krebs (TCA) cycle. Contains elementary particles that contains ATP synthase.Contains elementary particles that contains ATP synthase. Condensed form result from a conformational change inCondensed form result from a conformational change in

orthodox form.orthodox form.



MitchondriaMitchondria



Golgi Complex (apparatus)Golgi Complex (apparatus)

Like the packaging & shipping department.Like the packaging & shipping department.

Consist of Disk – shaped cisternae (saccules)Consist of Disk – shaped cisternae (saccules)

arranged in a stack arranged in a stack 2 major functions:2 major functions:

Processing of noncytosolic proteins synthesizedProcessing of noncytosolic proteins synthesized

in the RER.in the RER.

Membrane retrieval, recycling & redistribution.Membrane retrieval, recycling & redistribution.



Coated vesiclesCoated vesicles Characterized by a vesible cytoplasmic surface coat.Characterized by a vesible cytoplasmic surface coat.

2 varieties:2 varieties:

a.a. Clathrin coated vesiclesClathrin coated vesicles

Clathrin – 3 large & 3 small polypeptide chains thatClathrin – 3 large & 3 small polypeptide chains that

form a Triskelion (3 legged structure).form a Triskelion (3 legged structure).Formed during Endocytosis and associated with signalFormed during Endocytosis and associated with signal

directed transport.directed transport.

B.B. Non Clathrin coated vesicles. Involved in the transportNon Clathrin coated vesicles. Involved in the transport

of Proteins from RER to Golgi; form Golgi cisternae toof Proteins from RER to Golgi; form Golgi cisternae toanother; from Golgi complex to Plasma membrane.another; from Golgi complex to Plasma membrane.

* Associated with constitutive protein transport* Associated with constitutive protein transport



LysosomesLysosomes

Dense membrane bounded Organelles.Dense membrane bounded Organelles. Diverse morphology & size, with digestiveDiverse morphology & size, with digestive

enzymes.enzymes.

Formed when sequestered material fuses with aFormed when sequestered material fuses with a

late Endosome and Digestion begins.late Endosome and Digestion begins. Identified by Cytochemical staining for acidIdentified by Cytochemical staining for acid

Hydrolases.Hydrolases.

Possess special membrane protein & >40Possess special membrane protein & >40Hydrolases.Hydrolases.

Possess ATP powered Proton Pumps in theirPossess ATP powered Proton Pumps in their

membrane and acid ph (=5)membrane and acid ph (=5)



Types of LysosomesTypes of Lysosomes

A. A. Multivesicular bodiesMultivesicular bodies

B.B. Phagolysosomes.Phagolysosomes.

C.C. Autophagolysosomes Autophagolysosomes

D.D. Residual bodies.Residual bodies.



PeroxisomesPeroxisomes Also known as Microbodies Also known as Microbodies

Memebrane bounded, ovoid (+) for CatalaseMemebrane bounded, ovoid (+) for Catalase

Small organelles (0.15 – 0.25um dm)Small organelles (0.15 – 0.25um dm)

Originate from pre existing peroxisomes, divide byOriginate from pre existing peroxisomes, divide by

Fission.Fission.

Contains 3 oxidative enzymesContains 3 oxidative enzymes

1.1. D-amino acidoxidaseD-amino acidoxidase

2.2. Urate oxidaseUrate oxidase

3.3. Catalse & a number of other enzymes.Catalse & a number of other enzymes. Enzymes functions vary from Oxidation of fatty aciedsEnzymes functions vary from Oxidation of fatty acieds

to detoxification of substances such as Ethanol.to detoxification of substances such as Ethanol.

Lifespan ; 5 – 6 days.Lifespan ; 5 – 6 days.



CentriolesCentrioles Pair of Cylindrical rods (0.2um wide & 0.5 um Long)Pair of Cylindrical rods (0.2um wide & 0.5 um Long)

oriented at right angles to one another.oriented at right angles to one another.

Located in the Centrosome ( cell center)Located in the Centrosome ( cell center)

Self duplicating in the S phase of the cell cycle.Self duplicating in the S phase of the cell cycle.

Wall composed of 9 Triplets of /Microtubules (9+)Wall composed of 9 Triplets of /Microtubules (9+) Axoneme pattern) Axoneme pattern)

Associated with Microtubule organizing centers (MTOCs) Associated with Microtubule organizing centers (MTOCs)

dense pericentriolar bodies that give rise to Microtubulesdense pericentriolar bodies that give rise to Microtubules

* Form the Poles of the Mitotic spindles where Microtubules* Form the Poles of the Mitotic spindles where Microtubulesoriginate or converge.originate or converge.

* Form Basal bodies which give rise to the Axonemes of Cilia* Form Basal bodies which give rise to the Axonemes of Cilia

and Flagella.and Flagella.




Lifeless accumulations of MaterialsLifeless accumulations of Materials

Not metabolically activeNot metabolically active

Temporarily present.Temporarily present.

Composition:Composition:

a. Glycogena. Glycogen

b. Lipid dropletb. Lipid droplet

c. Lipofuscinc. Lipofuscin




GlycogenGlycogen

a. Small clusters or large aggregates (asa. Small clusters or large aggregates (as

rossettes)rossettes)

b. Electron denseb. Electron dense

c. 20 – 30 nm Beta particlesc. 20 – 30 nm Beta particles

d. Not membrane boundd. Not membrane bound

e. serve as a stored energy source.e. serve as a stored energy source.




Lipid DropletsLipid Droplets

a. vary markedly in sizea. vary markedly in size

b. Not membrane boundb. Not membrane bound

c. Storage forms of Triglycerides & c. Storage forms of Triglycerides &

Cholesterol.Cholesterol.




LipofuscinLipofuscin

a. membrane bound, electron – DENa. membrane bound, electron – DEN

b. represents a residue of undigestedb. represents a residue of undigested

materials.materials.

c. Age pigmentc. Age pigment

d. Most common in non-dividing cells andd. Most common in non-dividing cells and

Hepatocytes.Hepatocytes.



Nucleus & NucleolusNucleus & Nucleolus

One of the most important organelle in the cellOne of the most important organelle in the cell

Also called the brain center or the control center Also called the brain center or the control center

It controls the development of life and activities.It controls the development of life and activities. Made of dense area of DNA and protein.Made of dense area of DNA and protein.

It functions in RNA & Ribosome synthesis.It functions in RNA & Ribosome synthesis.



NucleolusNucleolus



NucleolusNucleolus The DNA in the chromosomes that controls life,The DNA in the chromosomes that controls life,

carries coded instructions to make RNA carries coded instructions to make RNA molecules with ribosomes build proteins to startmolecules with ribosomes build proteins to start

cell activity.cell activity.

The nuclear membrane is connected to the ER The nuclear membrane is connected to the ER and transport molecules thru out the cell.and transport molecules thru out the cell.

The ER with the Golgi bodies collect proteinsThe ER with the Golgi bodies collect proteins

made by the ribosomes and package them intomade by the ribosomes and package them into

them in vesicles and transport it out of the cellthem in vesicles and transport it out of the cell



Cytoskeletonytoskeleton



Cell skeleton with cytosol removedCell skeleton with cytosol removed



CentriolesCentrioles Appear as cylinders at right Appear as cylinders at right

angle to one another.angle to one another.

Help to form the spindleHelp to form the spindle

fibers, microtubules thatfibers, microtubules that

move around when the cellmove around when the cellis dividing.is dividing.



Basic components of the cell inBasic components of the cell in

electron microscopyelectron microscopy

Granules = 12 – 15 nm in dm, RNA and protein.Granules = 12 – 15 nm in dm, RNA and protein. Fibrils of 5 nm in dm, RNA and often closelyFibrils of 5 nm in dm, RNA and often closely

packed.packed. Chromatin both peripheral and nuclearChromatin both peripheral and nuclear

associated chromatin & as fine loops of associated chromatin & as fine loops of chromatin from the peripheral rim into thechromatin from the peripheral rim into theinterior.interior.

Proteinaceous, amorphous m,aterial uiusuallyProteinaceous, amorphous m,aterial uiusuallyoccuring in aggregations.occuring in aggregations.



Cell cycleCell cycle

Mitosis ( cell division)Mitosis ( cell division)

Interphase ( period between division), DNA isInterphase ( period between division), DNA is

synthesized ( DNA duplication or the “S” stage),synthesized ( DNA duplication or the “S” stage),Then G2 stage ( post duplication stage).Then G2 stage ( post duplication stage).

ProphaseProphase

MetaphaseMetaphase

Anaphase Anaphase

TelophaseTelophase



ChromosomesChromosomes

46 Human male somatic chromosomes46 Human male somatic chromosomes

Arrange in 23 pairs Arrange in 23 pairs 22 are autosomes22 are autosomes One pair formed the X & Y sex chromosomesOne pair formed the X & Y sex chromosomes

Result is 22 autosomes and one X or Y Result is 22 autosomes and one X or Y

chromosomes.chromosomes.



ChromosomesChromosomes

22 pairs of Female autosomes22 pairs of Female autosomes 1 pair of X chromosomes ( 2X Chrom.)1 pair of X chromosomes ( 2X Chrom.)

Diploid or double in number.Diploid or double in number. In the gonads, it contains half the numberIn the gonads, it contains half the number

or 23 chromosomes or “Haploid” andor 23 chromosomes or “Haploid” and

needs a special cell division calledneeds a special cell division called “Meiosis” or reduction division. “Meiosis” or reduction division. Result is 22 autosomes and 1 X chrom.Result is 22 autosomes and 1 X chrom.



Sex Chromatin (Barr Bodies)Sex Chromatin (Barr Bodies)

In normal female chromosomes contains 2 X chromosomes.In normal female chromosomes contains 2 X chromosomes. One appears small and indistinct but visible mass in the interphaseOne appears small and indistinct but visible mass in the interphase

nucleus “Barr bodies”. It is 1 um in dm.nucleus “Barr bodies”. It is 1 um in dm. It sometimes occur as “Drumstick” slender protrusion in the nucleusIt sometimes occur as “Drumstick” slender protrusion in the nucleus

seen in 20 – 70 % squamous epithelial cheek mucosa scrapping of seen in 20 – 70 % squamous epithelial cheek mucosa scrapping of somatic cells.somatic cells. It confirms the cell is from a female.It confirms the cell is from a female. Turner syndrome, female somatic cell has only 1 of the XTurner syndrome, female somatic cell has only 1 of the X

chromosomes.chromosomes. Klinefilters syndrome, it contains1 of the Y chromosomes & 2 orKlinefilters syndrome, it contains1 of the Y chromosomes & 2 or

more of the X chromosomes or even 3 Barr bodiesmore of the X chromosomes or even 3 Barr bodies



Cell DivisionCell Division

Depends on the demand for growth and replacements inDepends on the demand for growth and replacements intissues.tissues.

3 types of cell population3 types of cell population

1. Static = do not undergo DNA synthesis and cell1. Static = do not undergo DNA synthesis and celldivision,i.e., neurons of adults nervous system.division,i.e., neurons of adults nervous system.

2. Expanding = small proportion of DNA undergo DNA 2. Expanding = small proportion of DNA undergo DNA synthesis and cell division,i.e., liver, kidney, some glands.synthesis and cell division,i.e., liver, kidney, some glands.

3. Renewing population = need continuous replacement3. Renewing population = need continuous replacementor cell division for dying cells,i.e.,bone marrow, G.I. tract,or cell division for dying cells,i.e.,bone marrow, G.I. tract,epidermis.epidermis.



Cytokinesis = cell division of the nucleusCytokinesis = cell division of the nucleus

Karyokinesis = cell division of the nucleus.Karyokinesis = cell division of the nucleus.

Both can occur.Both can occur. Karyokinesis can occur without cytopkinesis as inKaryokinesis can occur without cytopkinesis as in

liver cells, osteoclasts, megakaryocytesliver cells, osteoclasts, megakaryocytes

results in binucleate or multinucleate cells.results in binucleate or multinucleate cells. In Sex cells or gametes(In Sex cells or gametes(ova/spermatozoaova/spermatozoa),),

karyokinesis involves Meiosis, haploidkaryokinesis involves Meiosis, haploid

chrom.number results so that after fertilization,chrom.number results so that after fertilization,

the fertilized ova regains the Diploid number of the fertilized ova regains the Diploid number of chromosomes in somatic cells.chromosomes in somatic cells.



Stages of MitosisStages of Mitosis

ProphaseProphase Chromatin threads condense ( shortened orChromatin threads condense ( shortened or

thickened), chromosomes becomes dark short andthickened), chromosomes becomes dark short and

visible. Centromere appears, Chromatids occur in eachvisible. Centromere appears, Chromatids occur in each

half with DNA.half with DNA.

Centrioles starts to duplicate, microtubules form, startsCentrioles starts to duplicate, microtubules form, starts

to separate between centrioles.to separate between centrioles.

Nucleolus gradually disappear, spindle fibers occurNucleolus gradually disappear, spindle fibers occur

Nuclear envelope starts to disintegrate, becomesNuclear envelope starts to disintegrate, becomes

thinner.thinner.



Metaphase, all chromatids move to the center of Metaphase, all chromatids move to the center of the cell in relation to the spindle and arrange inthe cell in relation to the spindle and arrange inequatorial plate.equatorial plate.

Anaphase, after completing the movements Anaphase, after completing the movements “Splitting the chromosomes occur”, move to “Splitting the chromosomes occur”, move toopposite poles of the cell. ( diploid set of 46opposite poles of the cell. ( diploid set of 46chrom.to each end).chrom.to each end).

Telophase, at each pole the chromosomesTelophase, at each pole the chromosomesdetach from the microtubules and thedetach from the microtubules and themicrotubules disintegrate. Each has its ownmicrotubules disintegrate. Each has its owndaughter cell with a nuclear envelop anddaughter cell with a nuclear envelop and

nucleolus are reforming and the centriole isnucleolus are reforming and the centriole isduplicating. The Plasma membrane constrictsduplicating. The Plasma membrane constrictsand the two new daughter cells are formed.and the two new daughter cells are formed.



What occurs after MitosisWhat occurs after Mitosis

Cell differentiationCell differentiation Protein synthesis secretions andProtein synthesis secretions and

Transcription of DNA Transcription of DNA Formation of 4 primary tissueFormation of 4 primary tissue

EpitheliumEpithelium

Connective tissueConnective tissue

MusclesMuscles Nervous tissues.Nervous tissues.



Thank youThank you

The Cell Histology

Documents

Transcript of The Cell Histology