Spleen Power

8/9/2019 Spleen Power

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The Spleen

Presented by

Prof. Dr. Maha Wagdy


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Spleen

Largest lymphoid organin the body located inleft upper quadrant ofthe abdominal cavity

Primary function is tofilter blood from antigen.

has no afferentlymphatic so it does notfilter lymph.


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Spleen


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CapsuleTrabecula

V

no cortex or medulla

A

Structure of spleen

Stroma peritoneum

SMF


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Fine stroma

Formed of reticularcells and fibers

More condensed inthe white pulp thanthe red pulp.


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Centralartery

PALS

Nodule

V

Red pulp

White pulp

no cortex or medulla

A

Structure of spleen

parenchyma

Sinusoids

Splenic Cords

Nodule


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White pulp


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White pulp

Primary lymphatic nodule formed ofBlymphocyte, macrophages.

1.Lymphatic nodule

Secondary lymphaticnodule has germinalcenterformed of

lymphoblast, plasmacell.

Central

artery


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2- Periarterial lymphatic sheath

Thymus dependantarea

Formed ofTlymphocytes

area around centralrtery


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WP = PALS + SNsWhite Pulp = PeriArteriolar Lymphoid

Sheath + Splenic Nodules

RP = Ss + SCs

Red Pulp = Sinusoids + Splenic Cords

Central artery

White to the nakedeye in fresh spleenviolet in H&E

Red to the naked eye infresh spleen, & in H&E

Cords are Swiss cheeseto the holes sinusoidsOr cords are spongetisuue and the sinusoidsthe spaces


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Central artery

Reticular fibers

Spleen stained by Silver


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Marginal Zone

Area betweenwhite pulp and redpulp.

composed of:1. marginal sinuses

2. interdigitatingdendritic cells

3. T & B

lymphocytes4. macrophages

5. plasma cells


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Importance of marginal zone

1. Site where blood born cells and antigens have theirfirst free access to the parenchyma of the spleen

2. Site ofentry ofT & B cell to the spleen.

3. Macrophages attack micro-organism in blood4. Interdigitating cell presents antigen to Lymphocyte

which initiate immune response.


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Red pulp

Formed of:1. blood sinusoids.

2. Splenic cords orBillroths cords:cellular massessupported by reticular

fibers and cells

Plasma cells

macrophages

blood cells T & B

lymphocytes


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WP = PALS + SNsWhite Pulp = PeriArteriolar Lymphoid

Sheath + Splenic Nodules

RP = Ss + SCs

Red Pulp = Sinusoids + Splenic Cords

Central artery

White to the nakedeye in fresh spleenviolet in H&E

Red to the naked eye infresh spleen, & in H&E

Cords are Swiss cheeseto the holes sinusoidsOr cords are spongetisuue and the sinusoidsthe spaces


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- The venoussinuses are similar

to tall woodenbarrels with bothends open.- The endothelialcells represented bythe wooden staves- The basal laminarepresented by thehoops around thebarrel

Endothelial cell

Endothelial cells are tall elongated with itslongitudinal axes parallel to longitudinal

axes of sinusoid

Basal lamina


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Blood sinusoid

Large, dilated irregularlumen

Endothelial cells are tallelongated in shape

Narrow intercelular cleft Associated macrophages

Discontinuous rings ofbasal lamina

Reticular fibersarranged in a transversedirection


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Blood circulation of the spleen


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Splenic circulation

Closed theory Open theory Combined theory


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Closed theory Open theory Combined theory


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SPLEEN Blood flow

Trabecular artery

Pulp veinSinusoids

Sheathed capillary (M&R)

Splenic V

Trabecular vein

Splenic Artery

Central artery[ ]

Simple arterial capillary

Penicillar arterioleArterial capillary


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Function of spleen

Site of activation of both T- and B-lymphocytes. These cell types interact withdendritic cells & macrophages that presentantigen to these lymphocytes.

Production of Ig Production of blood cells duringembryogenesis

Destruction of erythrocytes; old RBCs arerigid & are severely damaged when theypass through the slits (spaces) between thethe endothelial cells of splenic sinuses andphagocytosed by macrophages.

Temporary reservoir of blood


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PeritoneumCapsule SMFTrabeculae irregular

mainly from the hilumParenchyma red pulpand white pulp

N0 peritoneum

Capsule no SMFTrabeculae regularFrom the convex surfaceof the capsuleParenchyma cortex andmedulla


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SpleenLymph nodeDifferences

ySize of clenched fist.yKidney shaped of variable in sizeGeneralconsideration

yIn the left hypochondriumyScattered everywhere

ySingleySingle or multiple in groups

yCovered by peritoneumyNot covered by peritoneumCapsule

yThin capsule of collagenous and

elastic fibers with some smoothmuscle fibers

yThick capsule of collagenous and

elastic fibers

yNo lymphatic penetrate the capsuleyPenetrated by afferent lymphatics

yIrregular trabeculae arise mainly

from the hilum

yRegular thick trabeculae arise from

the capsule

Trabeculae

ySmooth muscle fibers are presentyDont contain smooth muscle fibers


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yLie in between the red and white pulp

divide the spleen into incomplete

compartments

yDivide the outer cortex into

regular compartments, while in

medulla, trabeculae are thin and

irregular

yDivided into white and red pulpyDivided into cortex and medullaParenchyma

yScattered all over the splenic tissueyConfined to cortical

compartments

Lymph nodules

yEither primary or secondary noduleyEither primary (formed mainly of

small B lymphocytes) or secondary

nodule (peripheral small B

lymphocytes and central pale

lymphoblasts that are termed

germinal center)

yPossess a central artery surrounded

by Periarterial lymphatic sheath (PALS)

formed of mainly T lymphocytes

yHave no central artery


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SpleenLymph nodeDifferences

yWhite pulp (lymphoid nodules)y splenic cords

yIn the form of cortical nodules, inner cortex

consists mainly of T lymphocytes never

arranged in nodules and medullary cords

formed of plasma cells, macrophages and Blymphocytes)

Dense lymphoidtissue

yRed pulp: modified loose lymphoid tissue in

the form of splenic cord containing

lymphocyte, plasma cell, macrophages and

blood cells

yIn between the nodules and the medullary

cords, containing lymphocytes, plasma cells

and macrophages

Loose lymphoidtissue

yContain blood sinusoidsyContain lymph sinuse

yPeriarterial lymphatic sheath areas around

the central arteries in lymphatic nodules

y inner cortex or paracortexThymic

dependent area( mainly T lymphocyte)

yOnly efferent lymphaticsyHas afferent and efferent lymphaticsLymphaticvessels

ymarginal sinuses present in marginal zones

between white and red pulp

ypost- capillary venules present in paracortexSite of entry of

T&B lymphocytes


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y Filtration of bloody Filtration of lymphFunctions

yImmunological responseyHumoral and cell mediated immunological

response

yDestruction of old RBCs

yTemporary reservoir for blood cells and platelets

yHaemopoietic organ during foetal life


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Histological organization of thymus and palatine tonsil


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QUIZ


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SPLEEN

1 - lymphoidfollicle (whitepulp)

2 - red pulp

3 capsule

4 - trabeculae(connectivetissue)


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The histological features of the spleen

include:

a. periarterial lymphatic sheaths.

b. cortex and medulla.c. Hassals corpuscles.

d. presence of crypts.


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Spleen Power

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