Histology of Spleen by Dr Roomi (26!04!12)

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HISTOLOGY OF SPLEENBY

DR. MUDASSAR ALI ROOMI (MBBS,M. PHIL)


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SPLEEN Largest lymph

organ It lies in the left

hypochondrialregion

it is covered all

over byperitoneumexcept at Hilum

Mesothelium(simple squamousepithelium) Lines

the outer surfaceof peritoneum.

capsule is denseirregularconnective tissuewhich sends in

Trebeculae intothe pulp of spleen4/26/12

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Stroma of spleen

1. C.T. Capsule

2. Trabeculae3. Reticulum:. it is Framework of

spleen

. Amorphous materialwith:

fine collagenfibers

Reticular Cells.

. Spaces in reticulum arefilled in by Splenic Pulp

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Parenchyma of spleen

Red pulp

white pulp

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White Pulp of spleen

(a) Includes Lymphoid tissue (bothdiffuse and nodular)

(b) Periarterial lymphaticsheats (PALS) surroundingsplenic arteriole.

replacing their Tunica adventitia.It contains T-lymphocytes.

(c) Splenic nodule (Malpighian corpuscle)

() B Lymphocytes (Bone marrowderived).

()

Visible to naked eye as whitedots. 0.25 1 mm..

() Germinal centre may be present.

() mantle arteriole enteringsplenic nodule from periarteriallymph sheath eccentric in

position (Central Artery) withdefinite T. Media.4/26/12 55


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Red Pulp

I. SPLENICSinusoids

. No lymphatics. Cells

modifiedreticular cells

Long axis ofcells liesparallel to thelong axis of

sinusoids.

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HISTOLOGY OF SPLLEN

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HOW TO DRAW IT?

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Differences between splenicsinuses and ordinary

capillaries1. Splenic sinusoids have irregularlumen and are highly distensible

2.

Have specialized endothelial cells(littoral cells) in their wall which arerod shaped and run longitudinally inthe vessel wall

3. Large gaps between the endothelialcells

4.

Incomplete basal lamina4/26/12 1010


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Functions of spleen

1. Filtration of blood: bacteria areremoved.

2.

Production of lymphocytes:occurs in the white pulp.

3. Destruction of old and worn out

erythrocytes: spleen is thegraveyard of RBCs. This function iscarried out by macrophages in thewall of sinusoids.

4. Stora e of blood:4/26/12 1111


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Identification points ofspleen

Peritoneal covering (serosa)

Red and white pulp

No differentiation into cortex andmedulla

Splenic nodules with central arteriole

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SPLLEN Vs Lymph Node

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SPLENIC CIRCULATION

Splenicartery : its 4-5rami enter the

Hilum. Along trabeculae

Finest arterioles

pass out ofTrebaculae

Adventitia

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Splenic Artery

5 or 4 branches

Enter trabelulae

Small arteriole branches

(Periart Lymphatic sheath surrounds it)

Central Arterioles in Splenic Nodule

Eccentric position

Branches to Splenic Nodule

Arterioles lose thin Lymph Sheath

divide in Red Pulp

Blood Circulation in Spleen

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eor es o oo ow nspleen

1. ClosedTheory

.

It states thatthe terminalarterialcapillaries opendirectly into thevenous sinuses.

2. OpenTheory

. It states that4/26/12 1616


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Histology of Spleen by Dr Roomi (26!04!12)

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