Histology of lymphoid organs

Question 1

B cell maturation occurs where in birds?

Answer 1

in Bursa Fabricius

Question 2

in mammals - B cell maturation?

Answer 2

bone marrow

Question 3

T cell maturation in mammals?

Answer 3

in thymus

Question 4

ruminants - B cell proliferation and maturation?

Answer 4

Peyer’s patches

Question 5

How do T cells and B cells proliferate?

Answer 5

Expansion of T cells
B cells form antibodies

Question 6

what cells mature to T cells?

Answer 6

bone marrow derived cells traverse the medulla and mature to T cells

Question 7

what happens to cells recognising self antigens?

Answer 7

they are removed from the thymus

Question 8

what happens to lymphoid tissue with sexual maturity?

Answer 8

it involutes with sexual maturity and is replaced by fat q

Question 9

lobules of thymus?

Answer 9

each have a cortex and a medulla

Question 10

thymus does not just have T cells - also?

Answer 10

thymus is supported by unique cytoreticulum of stellate, epithelial reticular cells and only a few reticular fibres

Question 11

What is the Bursa of Fabricius?

Answer 11

sac-like dorsal diverticulum of the proctoderm

Question 12

What is the Bursa of Fabricius unique to?

Answer 12

birds

Question 13

what epithelium lines the Bursa

Answer 13

pseudostratified columnar epithelium

Question 14

pB of f

Answer 14

primary tissue mainly but has some secondary function

Question 15

GALT?

Answer 15

gut associated lymphoid tissue

Question 16

where do peyer’s patches occur?

Answer 16

in the wall of the small intestines, especially ileum

Question 17

what do the capsule and trabeculae of the lymph nodes make up?

Answer 17

the connective tissue

Question 18

what do the lymphatic nodules and lymphatic tissue form?

Answer 18

the medullary cord

Question 19

what does the medullary cord contain?

Answer 19

lymphocytes, macrophages and plasma cells

Question 20

what does the paracortex of the medulla of the lymph nodes consist of?

Answer 20

T cells (CD4 T-helper cells & CD8 T-cytotoxic cells) and high endothelial venules (HEVs)

Question 21

what are high endothelial venules?

Answer 21

they are the main entry and exit site of (T and B) lymphocytes

Question 22

what are HEVs lined by?

Answer 22

by simple cuboidal epithelium

Question 23

what does the medulla of the lymph nodes express?

Answer 23

they express receptors (selectins) for antigen-primed lymphocytes
similar vessels are present aswell in the thymic cortex and Peyer’s patches

Question 24

what is the spleen characterised by?

Answer 24

by smooth muscle in the capsule and as a meshwork trabeculae

Question 24

what does white pulp tissue of the spleen include?

Answer 24

includes lymphoid tissue around arterioles

Question 25

what does the red pulp tissue of the spleen consist of?

Answer 25

consist of a loose vascular framework

Question 26

the thymus is not just supported by T cells - what else supports the thymus?

Answer 26

it is supported by a unique cytoreticulum of stellate, epithelial cells and only a few reticular fibres ALSO some dendritic cells, macrophages and other WBC

Question 27

Hassall's corpuscles - location?

Answer 27

these are found in the medulla of each lobe of the thymus

Question 28

What are Hassall's corpuscles?

Answer 28

they are concentric whorls of acidophilic and flattened reticular cells that may become swollen, keratinised and calcified centrally

Question 29

What is the Bursa of Fabricius?

Answer 29

it is a saclike dorsal diverticulum of the proctodeum it is unique in birds

Question 30

what epithelium lines the Bursa of Fabricius?

Answer 30

pseudostratified columnar epithelium

Question 31

describe the structure of the Bursa of Fabricius?

Answer 31

it has thick mucosal folds - polyhedral follicles it has a cortex and medulla

Question 32

what is found between the cortex and the medulla of the Bursa of Fabricius?

Answer 32

a layer of undifferentiated, epithelium-derived cells - ?capillary layer?

Question 33

apex of the Bursa of Fabricius?

Answer 33

epithelial tuft of simple columnar cells which contains lytic enzymes

Question 34

function of peyer's patches in ruminants?

Answer 34

they have an additional function as a primary lymphoid organ

Question 35

structure of ruminant peyer's patches?

Answer 35

aggregated lymphoid tissue with germinal centres (reflecting development of a specific immune response: secondary lymphoid tissue)

Question 36

peyer's patches are part of what?

Answer 36

part of MALT or GALT

Question 37

Where do peyer's patches occur?

Answer 37

in the wall of the small intestines, especially ileum

Question 38

what are peyer's patches covered by?

Answer 38

by a specialised follicle-associated epithelium, in which there are numerous M (micro fold) cells specialised for antigen uptake.

Question 39

what cells make up peyer's patches?

Answer 39

dendritic cells, macrophages, T and B cells

Question 40

what are the capsule and trabeculae of the lymph nodes?

Answer 40

they are connective tissue

Question 41

where does afferent lymph travel in lymph nodes?

Answer 41

travels within spaces (sinuses) which are present beneath the capsule and along trabecula of connective tissue that extends from the cortex into the medulla

Question 42

what are the sinuses called that the afferent lymph travel through in the lymph nodes?

Answer 42

subcapsular sinus