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HISTOLOGY DEPARTMENTMEDICAL FACULTY

UNIVERSITAS PADJADJARAN

LAB MANUALHematoimmunology System(Lymphoid System, CapillaryAnd Upper Respiratory Tract)

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I. LYMPHOID SYSTEM

I. LYMPHOID SYSTEM

The lymphoid (lymphatic) system consists

of organs whose tissues and cells impart

acquired immunity to organism.

-Immunity is the term use to describe this

protective response.

-Lymphoid organs : Thymus, spleen, lymph

nodes and tonsils

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C omponents lymphoid tissue :

1. Reticular connective tissue stroma2. Mesenchymal reticular cells

3. Epithelial reticular cells

4. Lymphocytes : T and B lymphocytes,Plasma cells

5. Macrophages

6. Antigen presenting cells

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Distribution of lymphoid tissue in thebody

Distribution of lymphoid tissue in thebody

Tonsils

Lymph nodes

LymphaticvesselsThymus

Spleen

Payerspatches of the ileum

Lymph nodes

Bone marrow

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Bone marrow

Stem cellproduces cells

that .

Bone marrowThymus

Remain in theMigrate to the

Interleukins

T lymphocytes

Migrating to non-thymic lymphoidtissue. producing

B lymphocytes

Immunoblasts

Killer

Generating

Helper Suppressor Tlymphocytes

Generating

T and B memorycells Plasma cells

Immunoblasts

Blood,lymph

When activatedby antigens,

produce

Producing

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The thymus is a central lymphoid organsituated in the mediastinum at about the levelof great vessels of the heart.

Structure :Lobe

Lobules (2) :

1. Cortex : small lymphocyte, epithelial reticular celland blood-thymus barrier.

2. Medulla : - Hassalls corpuscles

- Extend into the core of each of the

lobules

THYMUSTHYMUS

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4 . Medulla

5. Lobule

1. C apsule

3. C ortex

2. Interlobular trabeculae

6. Secondary (incomplete)trabeculae7. Medulla continuous

8. Lobule sectioned tangentially

9. Thymic corpuscle (Hassalscorpuscles)

10. C ortex

11. Interlobular trabeculae

12. Blood vessels in trabeculae

1. Venula

2. C apillary

3. Trabecula

4 . C ortex (thymic

lymphocytes)

8. Degenerating center of thymiccorpuscle)

6. Aggregations of reticularcells

7. Thymic corpuscle (Hassalscorpuscle)

5. Medulla (thymic lymphocytesand stroma)

9. Reticular cells in10. Isolated reticular cells

THYMUSTHYMUS

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Desmosome

Desmosome

Desmosome

Epithelialreticular cell

Lymphocytes

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Histogenesis and involution :

Third pharyngeal pouches (endodermal)

F unctions :

1. T-lymphocyte production

2. Hormone production : thymopoietin, thymosin

3. Blood-thymus barrier

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Lymph nodes are encapsulated sphericalor kidney-shaped organ composed of lymphoid tissue.

S cattered in group along lymphatic vessels inthe neck, axilla, groin, thorax and abdomen,they act as in-line filter of the lymph,removing antigen and cellular debris andadding Ig.

LYMPH NODESLYMPH NODES

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Structure (5) :

1. C ortex :

The dark-staining owing to presence of tightly packedlymphocytes.

S econdary lymphoid nodules (containing primarily Blymphocytes) with germinal centers.

2. Medulla :Lighter staining than cortex.

Composed of cords of lymphoid tissue (medullary cord)

separated by medullary sinuses.

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3. Paracortical zone :

This is the T-dependent region, lying between the

cortical lymphoid nodules and the medulla.Characteristized by the presence of many high-endothelial post capillary venules.

4 . Lymphatic Vessels :- Afferent lymphatic vessels

- Efferent lymphatic vessels

Afferent vessels subcapsular sinus peritrabecular

S inuses medullary sinuses efferent vessels

exiting through the hilum

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F unction :- Filtration of lymph

- Lymphocyte production (lymphopoiesis)- Immunoglobulin production

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1. Pericapsular fat andconnective tissue

2. C apsule

3. Lymphatic tissue

4 . C apsule andafferent lymphatics

5.C

ortex

6. Medulla

7. Trabeculae

8. Blood vesselsin trabeculae

9. Marginal(subcapsular)

sinus

10. Arterioles

11. Efferentlymphatic vessels

12. Hilus

13. Medullarysinuses

14 . Medullary cords

15. C ortical nodules

(Lymphatic nodules)16. Marginal(subcapsular) sinus

17. Germinal centers

18. Veins

LYMPH NODE (PANORAMIC VIEW)LYMPH NODE (PANORAMIC VIEW)

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The largest of the lymphoid organ, the spleen

lies in the upper left quadrant of the

abdominal cavity. It serves as theimmunologic filter of the blood.

SPLEENSPLEEN

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Structure (2) :1. Splenic pulp :

a. White pulp- Periarterial lymphatic sheaths (PAL S ) :

T dependent region- Peripheral white pulp (PWP) :

B lymphocytes and secondary lymphoid noduleb. Red pulp :- Red pulp cords (Billroths)- S plenic sinusoid- Endothelial cells (elongated on the sinusoids

long axis)c. The marginal zone :

- Border between the white and red pulp- Marginal sinuses

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2. Splenic circulation :a. Arterial supply :

Abdominal aorta S plenic arteryTrabecular artery Central arteriesPenicilliar arteriole Capillaries and sheeted

arterioles sinuses of

red pulpb. Open and closed theories of splenic circulation

c. Venous drainage

S inusoid red pulp veins Trabecular vein

S plenic vein inferior mesenteric vein

Hepatic portal vein liver

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F unctions :

1. Production of blood cells

2. Destruction of erythrocytes

3. Defense of the organism : filter for the blood4. S torage of blood

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7. Germinal center

8. Tangentialsection of asplenic nodule

9. C entral arteries(t.s) in splenicnodules

10. Venoussinuses in thered pulp

11. Trabecular veins

12. Trabeculae (t.s)13. Sheathed artery

14 . Pulp arteries(arterioles)

1. Peritoneumand capsule

2. Splenic nodules(white pulp)

3. Trabeculae

4 . Trabecular artery

5. Splenic cords inthe red pulp

6. C entral artery(l.s)

SPLEENSPLEEN

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Peripheral whitepulp (B cells)

Trabecular artery

Marginal zonesinuses

Periarterial lymphaticsheath (T cells)

C losecirculation

Trabecula

Peniciliar arteriole

Trabecular veins

Pulp vein

Opencirculation

Sheath

Marginal zone

sinuses

S

S

S

S

C entral artery

Sinusoid

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Sinusoid (closedcirculation)

Splenic cord

Sinusoid (open

circulation)

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This incompletely encapsulated lymphoidaggregates contain many lymphoid

nodules, they underlie the mucousmembranes (epithelial lining) of mouth andpharynx.

TONSILSTONSILS

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1. Stratified squamousepithelium

2. Lymphatic nodules

3. Tonsillar crypts

4 . Epithelium of crypt(tg.s)

5. Internodular septum (trabecula)

6. Skeletal musclefibers

7. Germinal center

8. Merging nodules

9. Internodular septum (trabecula)

10. F undi of crypts

11. Blood vessel inthe capsule

12. Skeletal musclefibers

PALATINE TONSILPALATINE TONSIL

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Skeletalmuscle

C rypt

Epithelium

Salivary gland

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Location

Number per individual

Number of crypts per tonsil

Epithelial covering

Capsule

P alatine TonsilsLateral walls of theoral pharynx, belowthe level of the soft

palate

2

10 20

Nonkeratinizedstratified squamous

Thick partial capsuleof dense connectivetissue

P haryngeal TonsilBack of thenasopharynx in themidline, above the levelof the soft palate

1

Surface pleated, but nocrypts

Ciliated pseudostratifiedcolumnar epithelium

Thin partial connectivetissue capsule

Lingual TonsilsAt the back of thetongue (floor of the

pharynx)

Small and numerous

One crypt per tonsil

Lightly keratinizedstratified squamousepithelium

No definitivecapsule

Table : Comparison of the TonsilTable : Comparison of the Tonsil

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K ey Features

Cortex and Medulla

Lymphoid nodules

Cords and sinuses

Unique structure

Thymus

Yes

No

No

Hassallscorpuscles

Lymph Nodes

Yes

Yes

Yes

Corticalnodules,

subcapsular sinus

Spleen

No

Yes

Yes

Centralarteries

Tonsils

No

Yes

No

Epithelialcovering

Table : Distinguishing structural features of the

lymphoid organs

Table : Distinguishing structural features of the

lymphoid organs

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Lymph node

Spleen

Outer cortex(mainly B cells)

Inner cortex(mainly T cells)Medullary cord(mainly B cells)

White pulp

Peripheral white pulp(mainly B cells)

Trabecula

Red pulp

Peripheral lymphaticsheath (mainly B cells)

Artery

Distribution of B and T cells in lymph nodes andspleen S, sinusoid

Distribution of B and T cells in lymph nodes andspleen S, sinusoid

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II. BLOOD VESSELS

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BLOOD VESSELSBLOOD VESSELS

Classified according to type and size

A. BLOOD C APILLARIES

J 7 9 Qm

S ingle layer endothelial cells with bulging nuclei

Basal lamina

Pericytes / mesenchymall cell

At the junction of a capillary, there is a ring of smooth muscle (precapillary sphincter)

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TYPES O F C APILLARIES

a. Continuous capillaries

S mooth nonporous

Junctional complexes

Muscles, the brain and peripheral nerves

b. Fenestrated capillaries

Fenestrae : +

Two types : - unobstructed pores

- Pores + thin diaphragma

Kidneys, intestines, endocrine glands

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c. S inusoidal capillaries (discontinuous)

Wide lumens

Follow a tortuous path

Gaps between endothelial cells

Fenestration ++

Phagocytic cells

Discontinuous basal lamina

Liver, spleen, bone marrow

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2a

1

b

3 Fenestrated

Continuous

Discontinuous

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III. RESPIRATORY SYSTEM

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There is 3 major part :1. Ventilating mechanism :

Includes :DiaphragmRib cageIntercostal muscle

Abdominal musclesElastic connective tissue in the lungs

A . Components and Basic Functions

of Respiratory System

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2 . Conducting portion :

It includes :

Nasal cavity

Nasopharynx

Larynx

Trachea

BronchiBronchioles

Terminal bronchioles

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3. Respiratory portionIt includes :

Respiratory bronchioles

Alveolar ducts

Atria

Alveolar sac

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The main divisions ofthe respiratory tract.The natural proportions

of these structureshave been altered forclarity; the respiratorybronchiole, for example

is in reality a shorttransitional structure

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a. General features :Ciliated pseudo stratified columnar

Goblet cellsb. Epithelial cell types :

Ciliated columnar cells

Mucous goblet Brush cellsBasal cellsSmall granule cells

B.Wall Structure

1. Respiratory epithelium

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Trachea

In the bronchi : smooth muscle cells encircle the walls

The muscle layer gradually decrease until it disappears

at the level of the alveolar ducts

2 . Lamina propria

3. Smooth muscle

Loose connective tissueMucous glands ( upper tract )

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D istinguishing features of respiratory tract components

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The nasal cavity consists of 2 structures :

1. The external vestibule

2. The internal nasal fossae

N asal Cavity

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The paranasal sinuses are blindcavities in :

Frontal

Maxillary

Ethmoid

Sphenoid bones

Paranasal Sinuses

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The upper part of the pharynx

N asopharynx

LarynxEpiglottis

Laryngeal Cartilages

Vocal apparatus

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Respiratory epithelium

Lamina propria : mixed seromucous glands

Presence of 16 - 20 C-shape cartilage rings

Smooth muscle bundles : trachealis muscle

T rachea

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T RACHEA

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T RACHEA(SECTION AL VI EW)

1. Perichondrium

2. Cartilage :matrix

3. Flattenedchondrocytes

4. Cartilage :territorialmatrix

5. Epithelium :pseudostratifiedciliated columnar

6. Basementmembrane

7. Elastic fibers(elasticmembrane)

8. Duct of a trachealgland (t.s)

9. Mucous alveoluswith a serousdemilune

10. Goblet cell

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