Lymphoid Organs 1

Question 1

Non encapsulated tissues and encapsulated tissues

Answer 1

Non encapsulated - diffuse lymphoid tissue, nodules, tonsils, payer’s patches, appendix

Encapsulated- lymph nodes, spleen, thymus

Question 2

All lymphoid tissues composed off

Answer 2

lymphocytes
Reticular cells and fibers make up the stroma (cortex of thymus is exception)
Lymphocytes make up the parenchyma

Question 3

Size categories of lymphocytes

Answer 3

90% small
10% large

Large have more cytoplasm but nucleus is same size

Question 4

2 functional types of small lymphocytes

Answer 4

B cells (20-30%)...give rise to plasma cells which produces ABs
T cells (70%) - CMI

Question 5

Lamina propria

Answer 5

Loose CT under epithelial membrane in rest, digestive, urinary and reproductive pathways where tissue fluid sampled for antigens

Question 6

Diffuse lymphoid tissues

Answer 6

Transient…contain macrophages, reticular cells, dendritic cells, B and T cells

Question 7

Lymphoid nodules

Answer 7

Structural and functional unit of the rest of diffuse lymphoid tissues…(all but lamina propria)

Do not have a CT capsule

Filter tissue fluid for antigens

Question 8

Primary nodule

Answer 8

Transient and round

Mostly B memory cells…reticular cells, some macros, dendritic and T cells present as well

Question 9

Secondary nodule

Answer 9

Where B cells have been exposed to antigens and produce more progeny

Germinal center of active B cells

Question 10

What is in each part of secondary nodule

Answer 10

Germinal center - APCs, macros, proliferating B lymph’s
Corona - mostly B memory
Between corona and germinal center - T helpers

Germinal center cells will have ore cytoplasm than corona cells

Question 11

Peyer’s patches

Answer 11

Found in submucosa and lamina propria of the lieum (being in lamina propria and move down into submucosa)
Bulge out from intestinal wall
No villi on top of them

Question 12

M cells

Answer 12

Specialized epithelial cells of mucosa associated lymphoid tissues that transport antigens from lumen to cells of immune system

Question 13

Tonsils

Answer 13

Aggregates of no-encapsulated lymphoid nodules
Partial CT capsule posteriorly but anteriorly lined by oral epithelium

3 types - lingual, palatine and pharyngeal

Epithelial lined crypts on all but pharyngeal

Question 14

Appendix

Answer 14

Large masses of lymphoid nodules present n lamina propria and submucosa of appendix

Form complete ring of lymphoid tissue

Materials can get trapped in here and they penetrate int the lamina propria

Question 15

Lymph node basic cellular structures

Answer 15

Cortex - contains B cell nodules (some activated and some not)
Paracortical area/deep cortex/paracortex/T cell zone - contains T cells
Medullary cords in the medulla - more B than T cells, also macrophages that scan lymph for antigens

Also will have multiple afferent vessels and one efferent vessel

Question 16

Lymphatic circulation

Answer 16

Afferent lymphatic vessels bring it in to the sub capsular sinus…then flows through narrow cortical/trabecular sinuses until it reaches medullary sinus and leaves via efferent lymphatic vessels

Question 17

Sinuses of lymph node

Answer 17

Filled with lymph and lined by reticular cells and macrophages…this slows down the flow of lymph

Question 18

Reticular meshwork of lymph nodes

Answer 18

Reticular cells secrete extensive reticular fiber meshwork

Dendritic reticular cells similar to macrophages that are APCs with long processes and a pale nucleus

Question 19

3 regions of lymph node in detail

Answer 19

Cortex - primary nodules (B-memory), secondary nodules (B-cell proliferation), Internodular region (T-helper)

Deep cortex - T-helper mostly with some naive and some CD8s

Medulla - medullary cords, sinuses, and hilus

Question 20

Blood flow of lymph nodes

Answer 20

Afferent artery in the hills to the cortex
Cortical capillaries to lymphatic nodules
Post capillary venues
Efferent veins to hilus

Question 21

Post capillary venues

Answer 21

Found in the deep cortical region
Lined with cuboidal cells
HEVs - T cells stick to them and migrate into the deep cortical region