Haemopoiesis

Question 1

What is haemopoiesis?

Answer 1

Formation of blood cells

Question 2

What is erythropoiesis?

Answer 2

Formation of red blood cells

Question 3

What is thrombopoiesis?

Answer 3

Formation of platelets

Question 4

What is myelopoiesis/granulopoiesis?

Answer 4

Formation of granulocytes

Question 5

What is lymphopoiesis?

Answer 5

Formation of lymphocytes

Question 6

What is cell production like in the steady state?

Answer 6

Cell loss is balanced by cell production

Question 7

What cell type would decrease first if haemopoiesis is switched off rapidly?

Answer 7

Neutrophils

Question 8

What are the steps in red cell production?

Answer 8

Pronormoblast - early normoblast - intermediate normoblast - late normoblast - reticulocyte - erythrocyte

Question 9

What is the ancestry of neutrophils?

Answer 9

Myeloblast - promyelocyte - myelocyte - metamyelocyte - band neutrophil - neutrophil

Question 10

What is the progenitor cell of platelets?

Answer 10

Megakaryocytes

Question 11

What do precursor cells develop from?

Answer 11

Mononuclear haemopoietic progenitor cells produced by haemopoietic stem cells

Question 12

What can mutlipotent progenitors give rise to?

Answer 12

Both myeloid (non-lymphoid) and lymphoid progeny

Question 13

What ability to stem cells have that is unique to them?

Answer 13

Ability to self-renew = this ability is lost as they differentiate and mature

Question 14

What state are most primitive progenitors (e.g stem cells) in during steady state haemopoiesis?

Answer 14

They are dormant

Question 15

Where do stem cells originate from embryologically?

Answer 15

The mesoderm

Question 16

How early in development are circulating committed progenitors detectable?

Answer 16

As early as week 5

Question 17

Where is the first site of erythroid activity during development?

Answer 17

The yolk sac = stops by week 10

Liver starts by week 6 and bone marrow by week 10

Question 18

Where is haemopoiesis restricted to in adults?

Answer 18

The bone marrow of axial skeleton, pelvis and proximal long bones

Question 19

Where can bone marrow biopsies be taken from?

Answer 19

Iliac crest in adults

Lower leg can be used in younger children

Question 20

What does the cellular compartment of the bone marrow contain?

Answer 20

Haemopoietic cells and non-haemopoietic cells (e.g adipocytes)

Question 21

What are the microscopic features of the bone marrow?

Answer 21

Cellular compartment, connective tissue matrix and vascular elements

Question 22

What vessels supply blood to the bone marrow?

Answer 22

The nutrient artery and periosteal network = bone marrow consumes 10-15% of cardiac output

Question 23

Where do arterioles of the bone marrow drain?

Answer 23

Into sinuses which further open into larger central sinuses

Question 24

How are sinusoids different from capillaries?

Answer 24

They are larger and have a discontinuous basement membrane

Question 25

How are sinusoids distributed in the bone marrow?

Answer 25

Radially around the central vein

Question 26

How are mature red cells released from the bone marrow into circulation?

Answer 26

They pass through fenestrations in endothelial cells

Question 27

What is release of mature red cells associated with?

Answer 27

Sinusoidal dilation and increased blood flow

Question 28

How do neutrophils enter the circulation form the bone marrow?

Answer 28

Actively migrate towards sinusoids down a chemokine gradient

Question 29

How do platelets enter the circulation from the bone marrow?

Answer 29

Megakaryocytes extend long branching processes called proplatelets into the sinusoidal blood vessels

Question 30

What are the different types of bone marrow?

Answer 30

Red marrow = haemopoietically active | Yellow marrow = fatty and inactive

Question 31

How does the type of bone marrow present change over time?

Answer 31

Increase in yellow marrow with age = older patients have reduced marrow cellularity

Question 32

What is the myeloid:erythroid ratio?

Answer 32

Relationship of neutrophils and precursors to proportion of nucleated red cell precursors

Question 33

What happens to the myeloid:erythroid ratio in haemolysis?

Answer 33

Reverses as there is an increase in erythroid production

Question 34

What are some regulators of haemopoiesis?

Answer 34

Intrinsic properties of cells Signals form immediate surroundings and periphery Haemopoietic niche

Question 35

What is the haemopoietic niche?

Answer 35

Specific anatomical area for optimal developmental signals

Question 36

What is the regulator of neutrophil precursor maturation?

Answer 36

G-CSF

Question 37

What regulates the growth and development of megakaryocytes from their precursors?

Answer 37

Thrombopoietin

Question 38

What are some investigations for haemopoiesis?

Answer 38

Routine = blood count, cell indices, morphology | Less common = bone marrow examination

Question 39

What are the investigations for mature non-lymphoid cells?

Answer 39

Blood count and morphology often enough | Cytochemistry rarely used

Question 40

How are mature lymphoid cells investigated?

Answer 40

Immunophenotyping = often require expression of antigens indicating lineage or stage of development

Question 41

What are the investigations for immature cells?

Answer 41

Immunophenotyping, clonogenic assays, animal models

Question 42

What is the purpose of immunophenotyping?

Answer 42

Identifies patterns of antigen expression unique to a cell lineage = use antibodies specific to different antigens

Question 43

How is immunophenotyping carried out?

Answer 43

Label cells with fluorochrome = emits certain colour of light when hit with a laser beam