Immune System

Question 1

Immune cells

Answer 1

B and T lymphocytes and Antigen Presenting Cells

Question 2

T-lymphocytes

Answer 2

Helper T cells

Cytotoxic T cells

Question 3

B-lymphocytes

Answer 3

Plasma cells (produce antibodies)
B memory cells

Question 4

Antigen Presenting Cells

Answer 4

APCs: macrophages and dendritic cells

Question 5

Lymphocyte development

Answer 5

Pre T and B cells need to arrive at primary lymphoid organ for education. Then exit to blood stream to travel to secondary lymphoid organ to interact with antigen (before this they are naive)

Question 6

Sources of lymphocytes

Answer 6

yolk sac, fetal liver and spleen, bone marrow

Question 7

Primary lymphoid organs

Answer 7

thymus (only T cells), bursa, Peyer’s patches, Bone marrow

Question 8

Secondary Lymphoid Organs (and tissues)

Answer 8

spleen, lymph nodes, bone marrow
Mucosa-Associated Lymphatic Tissue, MALT: Peyer’s patches (GALT, gut associated Lymphatic tissue), tonsils, Bronchus associated lymphatic tissue (BALT)

Question 9

addressins

Answer 9

aid in lymphocyte trafficking to target high endothelial venule

Question 10

Thymus

Answer 10

maturation/ education of T cells in cortex of thymus

decreases in size (involutes) with age becoming largely adipose tissue

Question 11

Staining in thymus

Answer 11

cortex is darkly stain outer portion

medulla is lighter staining inner portion

Question 12

location of thymus

Answer 12

cranial to heart

Question 13

Cortex of thymus

Answer 13

T lymphocyte replication
epithelial reticular cells
positive selection (MHC I and II recognition)

Question 14

epithelial reticular cells

Answer 14

isolate thymic cortex from medulla
Help from blood-thymus barrier
provide framework
help with positive and negative selection

Question 15

corticomedullary junction

Answer 15

negative selection (self antigen recognition)

Question 16

Medulla of thymus

Answer 16

far fewer T lymphocytes
support T lymphocyte development
Epithelial reticular cells very in shape
Thymic (hassall’s) corpuscles

Question 17

Germinal center

Answer 17

secondary nodule
darker part: B cells dividing, change conformation of antibody to fine tune response
Lighter part tests antibody

Question 18

Which part of lymph node is B cell rich?

Answer 18

primary nodule of cortex

Question 19

Lymph node

Answer 19

Con contain APCs, foreign particles, lymph is filtered as it winds through the node toward the sinus,

Question 20

Stroma of lymph node

Answer 20

capsule (dense irregular connective tissue), trabeculae, reticular fibers, sinuses (subcapsular, trabecular, medullary)

Question 21

Lymphoid nodules

Answer 21

B-cells, follicular dendritic cells, primary and secondary (germinal centers)

Question 22

reticular fibers in lymph node stroma

Answer 22

Type III collagen, framework for cellular attachment, arranged like a filter.
Retard movement of lymph through the sinuses and make the flow turbulent.

Question 23

Paracortex

Answer 23

inner cortex, T-cell rich, has APCs and HEVs (High Endothelial Venule)

Question 24

Medulla of cortex

Answer 24

Contains primed B and T cells and APCs
Medullary cords with plasma cells (B cells), T memory cells, and macrophages
medullary sinuses

Question 25

High endothelial venules

Answer 25

HEVs, how naive lymphocytes enter the lymph node, help with distribution of lymphocytes, simple cuboidal epithelium, can increase or decrease in length depending on needs
only transport lymphocytes and not RBCs

Question 26

What is unique about a pig lymph node?

Answer 26

Pig has multiple efferents and one afferent while most lymph nodes have one efferent and multiple afferents
Also pig has medulla on the outside and cortex on the inside instead of medulla on the inside and cortex on the outside like normal.

Question 27

Spleen function

Answer 27

Blood filtration
Mounting immune response to blood borne antigens (similar to lymph node, but for blood)
Storage of RBCs (depends on species)
hematopoiesis

Question 28

Spleen structure

Answer 28

capsule with trabeculae: fibroelastic tissue with smooth muslce
reticular fibers
Red and white pulp

Question 29

White pulp in spleen

Answer 29

immune function
PALS: Periarteriolar lymphoid sheath, from inner to outer:
T lymphocytes surrounding central artery
Primary and Secondary Nodules: B-lymphocytes
Marginal zones
Note: central artery is not the exact center

Question 30

Marginal zones

Answer 30

outer part of white pulp in spleen
B and T lymphocytes (plasma cells), APCs, 
macrophages attach microorganisms,
Circulating lymphocytes leave blood
Lymphocytes contact APCs

Question 31

Red pulp in spleen

Answer 31

RBC storage and removal
Splenic sinuses (only in dog, rat, and human): discontinuous endothelium and basal lamina
Red pulp vascular spaces
Macrophages and Periarteriolar macrophage sheaths (PAMS)
arterioles and venules

Question 32

Where are macrophages found in the spleen?

Answer 32

PAMS and vascular space of red pulp

Question 33

How can you differentiate PALS and the follicle on the slide?

Answer 33

You can’t, because T and B lymphocytes stain the same

Question 34

Mucosa-Associated Lymphatic Tissue

Answer 34

MALT, consists of lymphoid nodules and diffuse lymphatic tissue, no afferent ducts
Includes: Tonsils, BALT, GALT

Question 35

Primary vs Secondary lymphoid organ Peyers Patches

Answer 35

Secondary are more single sections and primary is long

Question 36

Hemal node

Answer 36

in deer, normal spaces have red blood cells and look darker and can be confused for melanoma