CPR 02 - Hematopoiesis

Question 1

Discuss where and when hematopoiesis occurs before birth.

Answer 1

Question 2

Where does hematopoiesis primarily occur after birth?

Answer 2

It only occurs in bone marrow after birth and most of it occurs in the vertebrae, pelvis, sternum, and ribs.

Question 3

Draw out the graph of the cellularity of hematopoiesis before and after birth.

Answer 3

Question 4

Where are most adult blood cells found and what special types of tissues (meaning they do not normally produce these tissues) can each stem cell population produce?

Answer 4

Question 5

Discuss the different stem cell potentcy classes.

Answer 5

Question 6

Draw out the hematopoiesis flow chart.

Answer 6

Question 7

Differentiate pluripotent stem cells, progenitor cells, and precursor cells.

Answer 7

Pluripotent Stem Cells - capable of producing all blood cell lineages and self renewal

Progenitor Cell - a cell that has the tendency to differentiate into another type of cell. Similar to a stem cell but with less specificity. When a progenitor cell divides it forms two precursor cells

Precursor Cell - a morphologically distinct, partially differentiated cell that is destined to become a specific cell type (unipotent). Also known as blast cells

Question 8

What is a stem cell niche and its primary functions?

Answer 8

A stem cell niche is defined as a spatial structure (microenvironment) in which stem cells are housed and maintained by allowing self-renewal in the absence of differentiation. A stem cell niche will actually inhibit differentiation.

Question 9

What creates the stem cell niche for HSCs (hematopoietic stem cells)? What is this structure composed of?

Answer 9

Bone marrow stroma composed of mesenchymal stem cells that resides in cancellous bone in the epiphysis of long bones.

Question 10

What is a vascular niche? Discuss its purpose and composition.

Answer 10

Question 11

What are the arrows pointing to?

Answer 11

Question 12

Discuss the general structure of bone marrow and the two types of bone marrow.

Answer 12

Question 13

What is this?

Answer 13

Bone marrow

Question 14

What do hematopoietic growth factors do?

Answer 14

They bind to progenitor cell receptors and trigger their differentiation into different cell types

Question 15

List the 3 major heamtopoietic growth factors, what tissue produces them, and what they do.

Answer 15

Question 16

What will occur is a hematopoietic cell does not receive a growth signal?

Answer 16

It will die

Question 17

What is myelopoiesis?

Answer 17

the production of bone marrow and of all cells that arise from it, namely, all blood cells.

Question 18

What are the various types of myelopoiesis?

Answer 18

Question 19

What is lymphopoiesis?

Answer 19

Formation of lymphocytes

Question 20

Where does erythropoiesis occur and what is the main stimulus for it?

Answer 20

It occurs in adult red bone marrow of certain bones and is stimulated primarily by hypoxia (causing the kidneys to release erythropoietin).

Question 21

List all the cellular stages of erythropoiesis. Describe the distinguishing characteristics of each cellular stage.

Answer 21

1. Pluripotent Stem Cell
2. Myeloid Stem Cell
3. Colony-forming unit-erythrocyte
4. Proerythroblast - no hemoglobin, large nucleus, basophilic cytoplasm
5. Basophilic (early) Erythroblast - some hemoglobin, condensing nucleus
6. Polychromatophilic Erythroblast - muddy cytoplasm
7. Orthochromatophilic (late) Erythroblast (normoblast) - increased hemoglobin
8. Reticulocyte - no nucleus, some ribosomes (blue with cresyl blue stain)
9. Erythrocyte - only hemoglobin, no ribosomes

Question 22

What controls granulocytopoiesis and how long does it typically take?

Answer 22

Granulocyte formation is controlled by cytokines; takes about 11 days

Question 23

List the cellular stages involved in granulocytopoiesis. Describe each stages defining characteristics.

Answer 23

1. Pluripotent Stem Cell
2. Myeloid Stem Cell
3. Colony-forming unit-granulocyte macrophage (for neutrophils only)
4. Myeloblast (common precursor) - no granules, cytoplasmic blebs
5. Promyelocyte - large nucleus, azurophilic granules
6. Myelocyte - condensed round nucleus, specific granules
7. Metamyelocyte - kidney shaped nucleus, specific granules
8. Band (stab) - C shaped nucleus, specific granules
9. Mature form of neutrophil, eosinophil, or basophil

Question 24

List the cellular stages involved in monocytopoiesis. Descibe each stages defining characteristics.

Answer 24

1. Pluripotent stem cell
2. Myeloid stem cell
3. Colony-forming unit-granulocyte macrophage
4. Monoblast - large, undifferentiated cells
5. Promonocytes - kidney shaped nucleus, azurophilic granules
6. Monocytes - “sky” blue cytoplasm, kidney shaped nucleus
7. Enter the circulation, proceed to tissue spaces, differentiate into macrophages

Question 25

List the cellular stages involved in throbopoiesis. Describe the defining characteristics of each stage.

Answer 25

1. Puripotent stem cell
2. Myeloid stem cell
3. Colony-forming unit-megakaryocyte
4. Megakaryoblast - endomitosis (replication of chromosomes without cell division)
5. Megakaryocyte - large multi-lobed nucleus
6. Platelets are formed from fragments of megakaryocyte cytoplasm (1000s per cell)
7. Platelet demarcation channels

Question 26

Answer 26

Question 27

List the cellular stages to lymphopoiesis. Describe the defining characteristics of each stage.

Answer 27

1. Pluripotent stem cell
2. Lymphoid stem cell
3. Colony forming units-lymphocyte (B=bursa equivalent; T=thymus)
4. Lymphoblasts - large, undifferentiated
5. Prolymphocytes - medium sized, condensing chromatin, no cell surface antigens
6. Some migrate from bone marrow to thymus and become T-cells, others remain in bone marrow, become B-cells, and migrate to lymph tissues

Question 28

From what part of the body is a bone marrow aspiration usually taken?

Answer 28

Iliac Crest

Question 29

Answer 29

Question 30

Answer 30