Lymph & Immunity

A selected location directory complements the realistic regional plates below. It is not a complete body-wide anatomical map; that primary visual remains staged.

Teaching references: OpenStax21.1 · Lymphatic organs and selected organisation · NIAID · Selected immune organs and cell roles

Teaching references: NLM · Specialised venules and lymphocyte entry · NLM · Node organisation and cellular traffic

Interstitial fluid enters a delicate lymphatic vessel

1

Blood capillary

Blood remains inside a separate microvascular channel.

More about blood capillary

Fluid exchange with surrounding tissue does not mean red blood cells normally pour into the lymphatic tube.

2

Blind-ended tip

A closed local end begins an initial lymphatic route.

More about blind-ended tip

Networks vary in shape. This tube has no open cut end that directly swallows a blood vessel.

5

Interstitial surroundings

Fluid and extracellular material surround the vessels.

More about interstitial surroundings

Lymphatic return supports volume and protein balance. It is not an optional overflow after universally fixed venous reabsorption.

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3

Initial lymphatic lumen

Collected interstitial fluid is called lymph once inside.

More about initial lymphatic lumen

Its composition depends on tissue and circumstances. A clear rendering is not a laboratory analysis or a guarantee that lymph contains no cells.

4

Delicate endothelial wall

Overlapping endothelial arrangements help permit entry.

More about delicate endothelial wall

Initial vessels differ from collecting vessels with muscular walls and internal valves. Exact cell junctions in the artwork are not independently verified.

Interstitial fluid enters a delicate lymphatic vessel · names and basic functions are visibleEnlarge view ↗

Interstitial fluid enters a delicate lymphatic vessel

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In many tissues at steady state, lymphatic return is important for sustained fluid and protein balance. The old picture of a fixed daily amount that is mostly reabsorbed at every venous capillary end is too universal.

Pressure, endothelial barriers and tissue conditions affect exchange. No universal daily litre quota, measured flow or completely sealed compartment is assigned here.

Teaching references: NLM · Lymphatic vascular structure and transport · NLM · Contemporary exchange and lymph return

Net transport reference: left → right · the static leaflet position is not an instantaneous flow measurement.

Wall forceValve functionExternal help

1. 1Muscular collecting wallLymphatic muscle can contract locally and help generate a pressure difference.Lymphatic muscle can contract locally and help generate a pressure difference.
2. 2Endothelial liningThe inner lining borders the lymph-filled lumen; it is distinct from surrounding muscle.The inner lining borders the lymph-filled lumen; it is distinct from surrounding muscle.
3. 3Thin valve leafletA flexible fold projects into the lumen, rather than forming a solid plug.A flexible fold projects into the lumen, rather than forming a solid plug.
4. 4Approaching free marginsThe free borders can meet during closure. Their position here is a static teaching snapshot.The free borders can meet during closure. Their position here is a static teaching snapshot.
5. 5Separate lymph lumenLymph travels within this channel; scattered drawn cells are not red blood cells or an identified immune subtype.Lymph travels within this channel; scattered drawn cells are not red blood cells or an identified immune subtype.
6. 6Leaflet attachmentThe leaflet joins the wall upstream of its free border in the illustrated left-to-right orientation.The leaflet joins the wall upstream of its free border in the illustrated left-to-right orientation.
7. 7Surrounding tissueMovement and compression outside the vessel can also contribute to transport.Movement and compression outside the vessel can also contribute to transport.

Enlarge Muscle supplies force. Valve leaflets limit reversal. ↗

Structure notes · further context

A valve is not a motor

Pressure differences act on flexible leaflets. Opening permits forward passage; closure limits backflow. The valves themselves do not provide a second central heart.

Initial versus collecting vessel

Delicate initial lymphatics collect interstitial fluid through specialised endothelial arrangements. Collecting vessels have different wall organisation and intraluminal valves; this muscular preparation must not be relabelled as the blind-ended initial vessel above.

More than one source of propulsion

Intrinsic lymphatic-muscle activity and external tissue movement can both contribute. Which component dominates depends on the vessel and conditions; a fixed wave speed, contraction frequency or human flow rate is not inferred here.

Muscle supplies force. Valve leaflets limit reversal. · atlas detail

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1. 1Muscular collecting wallLymphatic muscle can contract locally and help generate a pressure difference.Lymphatic muscle can contract locally and help generate a pressure difference.
2. 2Endothelial liningThe inner lining borders the lymph-filled lumen; it is distinct from surrounding muscle.The inner lining borders the lymph-filled lumen; it is distinct from surrounding muscle.
3. 3Thin valve leafletA flexible fold projects into the lumen, rather than forming a solid plug.A flexible fold projects into the lumen, rather than forming a solid plug.
4. 4Approaching free marginsThe free borders can meet during closure. Their position here is a static teaching snapshot.The free borders can meet during closure. Their position here is a static teaching snapshot.
5. 5Separate lymph lumenLymph travels within this channel; scattered drawn cells are not red blood cells or an identified immune subtype.Lymph travels within this channel; scattered drawn cells are not red blood cells or an identified immune subtype.
6. 6Leaflet attachmentThe leaflet joins the wall upstream of its free border in the illustrated left-to-right orientation.The leaflet joins the wall upstream of its free border in the illustrated left-to-right orientation.
7. 7Surrounding tissueMovement and compression outside the vessel can also contribute to transport.Movement and compression outside the vessel can also contribute to transport.

Original generated teaching preparation, not microscopy. Left-to-right is the reference direction for net transport. One nearly apposed valve pair is shown, not a complete pumping cycle or an entire lymphangion between serial valves. The controls locate different jobs; they do not animate leaflet opening.

Open full-resolution illustration ↗ · Image only; editable labels and explanations remain in this lesson.

The collecting wall helps generate pressure

Lymphatic-muscle contractions can help drive lymph. They cooperate with surrounding tissue forces; one frozen image cannot supply a measured contraction cycle.

Wall force

Lymphatic-muscle contractions can help drive lymph. They cooperate with surrounding tissue forces; one frozen image cannot supply a measured contraction cycle.

Valve function

Forward and reverse pressure conditions act on the leaflets differently. Closure limits backflow; a valve does not actively push fluid by itself.

External help

Skeletal movement, breathing-related changes and other external forces can support transport. These influences vary with location and circumstances.

The controls change the learning focus on the same anatomy, not the valve position or a measured time sequence.

Supporting transport comparison beside the realistic initial-vessel plate. Valve pairs and contraction are explained without depicting that thin initial tube as a muscular collector.

Teaching references: NLM · Lymphatic vascular structure and transport · NLM · Contemporary exchange and lymph return

Vessels in the meninges contribute to brain-border drainage; this is not the same as ordinary lymphatic capillaries throughout brain parenchyma. Detailed CNS drainage contributions remain an active research area.

Teaching references: NCBI · Thoracic duct and variation · NLM · Thoracic duct / cisterna-chyli variability · NLM · Meningeal lymphatic context

The spleen processes blood in different tissue compartments

4

White-pulp region

Lymphoid tissue supports responses to blood-borne material.

More about white-pulp region

T-cell and B-cell neighbourhoods relate to arterial context. A pale generated region does not identify every immune population.

1

Splenic surface

An organ in the left upper abdomen lies beside the stomach.

More about splenic surface

The isolated view explains tissue organisation; it is not a complete body locator or a measured individual organ.

2

Capsule / support

A connective envelope and inward supports organise the organ.

More about capsule / support

Subtle trabeculae carry support and vascular context. Their exact extent in this generated cutaway is illustrative.

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5

Splenic artery

Arterial blood supplies the organ at the hilum.

More about splenic artery

Blood enters this circulation separately from lymph draining tissues elsewhere. Fine internal branches are not a complete angiogram.

6

Splenic vein

Venous blood leaves and joins portal circulation.

More about splenic vein

The splenic vein connects with the portal system. Its blue colour is an orientation convention, not a statement that it transports lymph.

3

Red pulp

Blood-rich tissue participates in red-cell assessment and removal.

More about red pulp

Macrophages and specialised circulation help process aged or altered blood cells. This is not a simple mechanical sieve with identical holes.

The spleen processes blood in different tissue compartments · names and basic functions are visibleEnlarge view ↗

The spleen processes blood in different tissue compartments

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Red pulp contributes to handling aged or altered red cells; white pulp organises immune responses to blood-borne material. The splenic vein joins portal circulation.

A human spleen should not be taught by relabelling a node cortex and medulla. Fine circulation and marginal/perifollicular compartments also differ between species.

Teaching references: NCBI · Normal spleen anatomy · NLM · Human versus rodent splenic compartments

Thymic tissue supports developing T-cell selection

3

Cortical region

A densely cellular outer region supports developing thymocytes.

More about cortical region

Thymocytes interact with specialised epithelial and other cells. No coloured nucleus verifies a particular developmental or receptor state.

2

Septa / vascular support

Connective extensions carry support between lobular portions.

More about septa / vascular support

Real medullary tissue is continuous across adjoining regions. A two-dimensional cut cannot establish every connection.

5

Epithelial profile context

Concentric epithelial profiles occur in thymic medullary tissue.

More about epithelial profile context

The visible form is illustrative, not a verified Hassall corpuscle specimen. Its presence does not prove that every selection event occurs inside it.

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1

Connective capsule

An outer envelope surrounds thymic tissue.

More about connective capsule

Connective extensions divide lobular portions. The thymus is not a lymph node with afferent lymph filtering through follicles.

4

Medullary region

A less densely packed internal region supports further selection.

More about medullary region

Negative selection is not restricted exclusively to one region. Some self-reactive cells are removed while other outcomes include regulatory-cell development.

6

Vascular context

Blood supports the living tissue and cellular traffic.

More about vascular context

Vessels are separate from developing lymphocytes. Precise microvascular routes and developmental changes remain outside this illustration’s verification scope.

Thymic tissue supports developing T-cell selection · names and basic functions are visibleEnlarge view ↗

Thymic tissue supports developing T-cell selection

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Selection helps establish useful recognition of peptide–MHC context and limit harmful self-reactivity. Outcomes are more complex than “all cells pass” or “all self-reactive cells die”; regulatory-cell development is part of the wider story.

Medullary tissue connects across adjoining lobular regions in three dimensions. With age, much thymic tissue is replaced by fat, although tissue can remain; a young tissue model is not every adult appearance.

Teaching references: NCBI · Thymus organisation · NCBI · Thymic development and selection

Teaching references: NIAID · Selected immune organs and cell roles · NLM · Normal immune-cell and complement coordination

Teaching references: OpenStax21.2 · Barriers and innate coordination · NLM · Normal immune-cell and complement coordination

Supporting normal recruitment sequence. Cell type, vessel context and timing vary; no exact adhesion-molecule network, clinical inflammation grading or experimental manipulation is claimed.

Teaching references: OpenStax21.2 · Barriers and innate coordination · NLM · Normal immune-cell and complement coordination

Teaching references: NCBI Immunobiology · Selected immune principles · NLM · Normal immune-cell and complement coordination

Antigen displaySpecific recognitionActivation context

1. 1Lymphoid meeting environmentOther cell profiles and a tissue framework place the encounter within a local cellular neighbourhood.Other cell profiles and a tissue framework place the encounter within a local cellular neighbourhood.
2. 2Antigen-presenting cellThe left representative cell supplies a surface on which processed peptide can be presented with MHC II.The left representative cell supplies a surface on which processed peptide can be presented with MHC II.
3. 3Presenter nucleusThe cutaway exposes this cell’s internal compartment; it does not show antigen entering the neighbouring nucleus.The cutaway exposes this cell’s internal compartment; it does not show antigen entering the neighbouring nucleus.
4. 4Separate membrane contactOpposing cell surfaces meet without fusing their cytoplasm or engulfing one another.Opposing cell surfaces meet without fusing their cytoplasm or engulfing one another.
5. 5Representative CD4 T cellA suitable T-cell receptor recognises peptide–MHC II together; touching a cell is not sufficient evidence of activation.A suitable T-cell receptor recognises peptide–MHC II together; touching a cell is not sufficient evidence of activation.
6. 6T-cell nucleusThe large internal nuclear compartment remains within a different cell. Subsequent responses are not read from generated texture.The large internal nuclear compartment remains within a different cell. Subsequent responses are not read from generated texture.

Enlarge Two intact cells meet; information is presented at their surfaces. ↗

Structure notes · further context

Processed peptide, not a whole microbe

In this conventional CD4 example, antigen-derived peptides are displayed with MHC II on the presenting cell. A T cell does not need to swallow that cell to recognise the display.

Recognition needs context

Naive T-cell activation also depends on co-stimulatory and local signalling context. B7–CD28 is an important co-stimulatory example; the artwork does not enlarge invented receptor shapes or claim to measure these signals.

Keep B-cell and CD8 routes distinct

B-cell receptors can bind suitable antigen directly. Conventional CD8 T-cell recognition uses peptide–MHC I. The single CD4 preparation is not silently relabelled as those different interactions.

Two intact cells meet; information is presented at their surfaces. · atlas detail

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1. 1Lymphoid meeting environmentOther cell profiles and a tissue framework place the encounter within a local cellular neighbourhood.Other cell profiles and a tissue framework place the encounter within a local cellular neighbourhood.
2. 2Antigen-presenting cellThe left representative cell supplies a surface on which processed peptide can be presented with MHC II.The left representative cell supplies a surface on which processed peptide can be presented with MHC II.
3. 3Presenter nucleusThe cutaway exposes this cell’s internal compartment; it does not show antigen entering the neighbouring nucleus.The cutaway exposes this cell’s internal compartment; it does not show antigen entering the neighbouring nucleus.
4. 4Separate membrane contactOpposing cell surfaces meet without fusing their cytoplasm or engulfing one another.Opposing cell surfaces meet without fusing their cytoplasm or engulfing one another.
5. 5Representative CD4 T cellA suitable T-cell receptor recognises peptide–MHC II together; touching a cell is not sufficient evidence of activation.A suitable T-cell receptor recognises peptide–MHC II together; touching a cell is not sufficient evidence of activation.
6. 6T-cell nucleusThe large internal nuclear compartment remains within a different cell. Subsequent responses are not read from generated texture.The large internal nuclear compartment remains within a different cell. Subsequent responses are not read from generated texture.

Original generated cellular teaching illustration, not a micrograph or a cell-identification test. The assigned roles represent a conventional dendritic-cell–CD4 T-cell encounter. Cell shape and colour do not establish molecular identity; exact receptor geometry, peptide location and synapse organisation are not resolved.

Open full-resolution illustration ↗ · Image only; editable labels and explanations remain in this lesson.

A surface display carries processed information

The presenting cell displays suitable peptide with MHC II. This is a conventional CD4 example, not a whole pathogen being passed into a T cell.

Antigen display

The presenting cell displays suitable peptide with MHC II. This is a conventional CD4 example, not a whole pathogen being passed into a T cell.

Specific recognition

The receptor responds to peptide–MHC context. A nearby T cell with a different specificity need not respond to the same display.

Activation context

Co-stimulation and local signals help determine the outcome. The preparation shows an encounter; neither the highlight nor the cell colour proves that an immune response has begun.

The controls change the learning focus on the same anatomy, not the cell’s identity or a measured time sequence.

Supporting recognition comparison. Co-stimulation and local signals influence activation; binding alone is not a universal guarantee of an effective response. Non-conventional lymphocyte recognition is outside this introductory scope.

Teaching references: OpenStax21.3 · T-cell recognition · OpenStax21.4 · B cells and antibodies · NCBI Immunobiology · Selected immune principles

Antibody-producing cells and memory B cells are different outcomes. Not all B-cell responses require the same T-cell help; this overview does not turn one common pathway into an exception-free rule.

Teaching references: OpenStax21.4 · B cells and antibodies · NLM · Normal immune-cell and complement coordination

Innate and adaptive activity overlap and communicate. They are not two mutually exclusive switches, and “innate” should not be simplified into an absolute claim that no altered response history can ever occur.

Teaching references: OpenStax21.3 · T-cell recognition · OpenStax21.4 · B cells and antibodies · NLM · Normal immune-cell and complement coordination

Teaching references: NLM · Lymphatic vascular structure and transport · OpenStax21.1 · Lymphatic organs and selected organisation

Record descriptions checked; slide pixels not acquired or presented here. The rendered plates are original educational illustrations, not microscopy, clinical imaging or diagnostic evidence.

Teaching references: Duke · Identified lymphoid tissue records · NLM · Human versus rodent splenic compartments

Teaching references: NIAID · Selected immune organs and cell roles · NLM · Lymphatic vascular structure and transport