Lab 8: The Immune System | Lymphoid Tissues &Organs

Question 1

Identify the cells indicated by the arrows and give one function that these
cells perform.

Question 2

Identify the circled area and describe:

Answer 2

This is the ileum, part of the small intestine. Although we have not
examined the GI tract in detail yet, identify the gut lumen, epithelium
CT and muscle. Embedded in the submucosa (CT) are confluent
groups of lymphoid nodules (within the oval). Solitary nodules are also present.

Question 3

Peyer’s patches: Identify numbered areas and describe

Answer 3

Peyer’s patches are accumulations of lymphatic nodules that can involve both layers of CT in the wall, being in the submucosa and the lamina propria, often confluent (contiguous) on one side of ileum, as opposed to single nodules. Nodules often have a cap of small lymphocytes

(1) outside of a core of activated lymphocytes and antigen-presenting cells called the germinal center
(2) Note diffuse infiltration of white blood cells in the loose CT especially
in the lamina propria.
(3)

Question 4

What is within the circle?

Answer 4

Within the circle are the finger like-extensions of villi on the right and a
shorter villus filled with lymphocytes. The lumen in this region is covered
by M-cells. Lymphocytes lie beneath the thin portions of the cells and
receive antigenic peptides

Question 5

Examine the outer cortex and find if possible:

• containing nodules
• (follicles) inner paracortex
• without nodules
• medulla

Question 6

Examine the outer cortex and find if possible:

• containing nodules
• (follicles) inner paracortex
• without nodules
• medulla

Question 7

Examine the outer cortex and find if possible:

• containing nodules
• (follicles) inner paracortex
• without nodules
• medulla

Question 8

Identify structures 1-6:

Where would you expect to fine the high
endothelial venules?

Answer 8

This lymph node shows many of the key features. Note the capsule (1), where afferent lymphatic vessels enter, the subcapsular sinus (2), the trabeculi(3) and trabecular sinuses (4) (or cortical and paracortical sinuses,) and the medullary cords and sinuses (5). Note the cortex, the
paracortex and the medulla, as well as the hilus (6).

Question 9

Find elongated nuclei:

What is the collagen type?

Answer 9

Note the fibers in the capsule, along and projecting into the cortical sinuses and supporting the lymph node. Reticular cells lay down the reticular fibers. Look for cells with elongated nuclei, particularly in the sinus spaces.
Collagen type:

Question 10

Identify 1-4:

Answer 10

1. Capsule
2. Trabeculum
3. White pulp
4. Red pulp

Question 11

Identify 1 and 2:

Question 12

Identify: 4-8, 10, 13

Answer 12

Red pulp:
4 arteriole
5 endothelial cell
6 reticular cells
7 interstitial space
8 venous sinusoid
10 macrophages
13 hematopoiesis

Question 13

Describe:

Answer 13

A thin capsule surrounds the thymus. Note the incomplete septa that divide the
thymus into lobules. The lobules have a dark staining cortex without nodules and a paler staining central medulla that is irregular in shape and intercommunicates with other medulla throughout the organ.

Question 14

Describe:

Answer 14

Note the incomplete septa that divide the thymus into lobules. The lobules have a dark staining cortex without nodules and a paler staining central medulla that is irregular in shape and intercommunicates throughout the organ. The medulla has concentrically arranged epithelioreticular cells (type VI) that form the thymic or Hassall’s corpuscles. Both the cortex and medulla have epithelioreticular cells forming their framework.

Question 15

What is displayed in this image?

Answer 15

This light micrograph shows a thymus with a thymic or Hassall’s corpuscle

Question 16

Describe:

Answer 16

Note the high endothelial venules in the paracortical zone. The lymphocytes
return to the lymph nodes, leaving the blood through these high endothelial
venules by migrating between the endothelial cells. They can re-circulate many
times this way. High endothelial venules can also be found in spleen, tonsils and Peyer’s patches as well.

Question 17

Identify E and L.

Answer 17

An example of a postcapillary venule with an abnormally thick endothelium (E = endothelial cell). A lymphocyte (L) is squeezing through the endothelial cell.

Question 18

Identify E, L, R, N:

Answer 18

• E: cubodial epithelium
• L: lympocyte
• R: red blood cells
• N: neutrophil

Question 19

Identify: LB

P:

arrows:

Answer 19

Question 20

Identify: arrows, G

Answer 20

see attached text

Question 21

Identify: S, Sh, N, C.

Answer 21

see attached text

Question 22

Identify N, M

Answer 22

see attached text

Question 23

Identify: N, O, S, E, P, PC

Answer 23

see attached text

Question 24

Identify: ly

Answer 24

see attached text

Question 25

Describe this image:

Answer 25

The black material in this unstained section is an extracellular tracer that was injected into the bloodstream. The insert shows that passage from the lumen to the cortex is blocked by endothelial tight junctions. What gets across is taken up by macrophages, processes of which are above and below the capillary. Sheets of cytoplasm of epithelial reticular cells are visible around the capillary.

Question 26

What is the arrow pointing to:

Answer 26

See attached text:

Question 27

Identify L:

Answer 27

See attached text:

Question 28

Identify T, E and circles

Answer 28

See attached text: