Bone Marrow, Blood, Thymus, Lymph, and Spleen

Question 1

_____ derived hemangioblasts differentiate into enothelial cells and _______ stem cells at the start of embryonic period (week 3).

Answer 1

Mesoderm

Hematopoetic

Question 2

Hematopoetic stem cells organize as _____ _____ in extra-embryonic mesoderm. From there, they migrate to the _____, which remains the major hematopoetic organ until month _____, when stem cells colonize the bone marrow.

Answer 2

Blood islands

Liver

7

Question 3

Hematopoetic SCs in the bone marrow form progenitor cells that proliferate into _____ (same thing as saying progenitor cell) when experimentally injected into spleen. Progenitor cells give rise to 5 precursor cell classes:

1. _____
2. _____
3. _____
4. _____
5. _____

Answer 3

CFUs

1. Erythrocytic (CFU-E)
2. Granulocytic (CFU-GM)
3. Monocytic (CFU-GM)
4. Lymphocytic (CFU-L)
5. Thrombocytic (CFU-Meg)

Question 4

Erythropoeisis takes __-___ days

Answer 4

7-8

Question 5

Granulopoeisis takes ___-___ days, and ends with ______-shaped nuclei formation (band cells).

Answer 5

14-16 days

Horseshoe-shaped

Question 6

What is the decreasing order of presence of leukocytes in the blood?

Answer 6

Neutrophils>Lymphocytes>monocytes>eosinophils>basophils

Question 7

Blood-thymus barrier in the cortex consists of ERCs, ____ junctions of capillary endothelium, and macrophages. Circumvention of the barrier by non-self or self-antigen drives reactive T-cells into _____ –> no immune rxn in thymus.

Answer 7

Tight

Apoptosis

Question 8

____ corpuscles in the Thymic medulla are surrounded by ERCs that produce _____ –> induces development of regulatory T-cells that terminate the immune response outside the Thymus.

Answer 8

Hassal’s corpuscles

Cytokines

Question 9

Lymphatic capillaries are particularly abundant in organ systems that are open to the ______ environment.

Answer 9

External

Question 10

____ valves ensure the unidirectional flow of lymph toward the lymph nodes.

Answer 10

Bicuspid valves

Question 11

Lymph nodes are encapsulated by ____ connective tissue. Do they exhibit darker or lighter staining in the cortex vs the medulla, and what accounts for the dark staining?

Answer 11

Dense

Dark cortex/Light medulla –> Cortex stains darker bc collection of antigen-activated B-cell progeny

Question 12

Arterial blood that enters lymph node cortex and medulla drains into ___ _______ Venules that reside at the corticomedullary border.

Answer 12

High Endothelial venules

Question 13

Simple cuboidal endothelium of HEVs expresses cell _____ molecules that facilitate selective migration of circulating ___ and ___ cells into the lymph nodes.

Answer 13

Adhesion

T and B-cells

Question 14

Lymph flows into lymph nodes from afferent lymph vessels into the ______ sinus. From there, it drains directly into the _____ sinus. The sinuses are lined by _______ endothelium, where antigens are filtered from the percolating lymph by adjacent lymphocytes and macrophages.

Answer 14

Subcapsular sinus

Cortical sinus

Question 15

____-cells selectively activated by incoming antigens replicate in the cortex to form lymphoid _____. ____ cells derived from the progeny B-cells comprise the paler-staining germinal centers within the _____.

Answer 15

B-cells

Nodules

Plasma

Nodules

Question 16

Lymph drains from cortical sinuses into the _____ sinuses that surround _____ cords (comprised of aggregates of antigen-activated lymphocytes and plasma cells that migrated from the cortex).

Answer 16

Medullary

Medullary

Question 17

MALT stands for? Like lymph nodes, what forms the lymphoid nodules in MALT?

Answer 17

Mucosa associated lymphoid tissue

Antigen-activated B-cells form nodules with interspersed T-cells.

Question 18

The spleen is comprised of splenic pulp, consisting mostly of extravasated _______ (red pulp), lymphoid nodules (_____ pulp), and a fine meshwork of type ____ collagen.

Answer 18

RBCs

White pulp

Type III

Question 19

Splenic capillaries are ____-ended, which means what for the blood flowing through them?

Answer 19

Open-ended, so blood flow right out of them into the red pulp.

Question 20

Extravasated RBCs squeeze through slit-like spaces between endothelial cells that line _____ _____, which interweave throughout the red pulp. Aged RBCs lose their pliability, so they remain in the pulp and are removed how?

Answer 20

Venous Sinusoids

Phagocytically by resident macrophages

Question 21

Blood-borne antigens that enter the spleen are either selectively bound by extravasated _______, or they are phagocytized by the resident macrophages. Proliferation of _____-activated ___-cells form the lymphoid nodules of the white pulp.

Answer 21

Lymphocytes

Antigen-activated B-cells

Question 22

Erythropoetin is secreted by interstitial ________ cells of the kidney in response to _____ (high or low oxic conditions?)

Answer 22

Interstitial Peritubular cells

Low