Haemopoiesis

Question 1

A 50-year-old individual is being investigated for a suspected bone marrow malignancy. Which of the following anatomical sites is most appropriate for bone marrow examination?

Answer 1

Posterior iliac crest

Question 2

What is haemopoesis?

Answer 2

Formation of blood cells

Question 3

What are the white cells?

Answer 3

Granulocytes; neutrophils, eosinophils, basocphils
Monocytes
Lymphocytes; B cells, T cells, NK cells

Question 4

What is the function of platelets?

Answer 4

Primary haemostasis

Question 5

What is the function of erythrocytes?

Answer 5

Oxygen and carbon dioxide transport

Question 6

What are the different forms of haemopoiesis?

Answer 6

Myelopoiesis/ granulopoiesis
Erythropoiesis
Thrombopoiesis
Lymphopoiesis

Question 7

What is are the life spans of red cells, neutrophils and platelets?

Answer 7

Red cells; 120 days
Neutrophils; 7-8 hours
Platelets; 7-10 days

Question 8

What is a blast?

Answer 8

Nucleated precursor cell
Erythroblasts (Red cells)
Myeloblasts (granulocytes)

Question 9

What is a megakaryocyte?

Answer 9

Platelet precursor

Polyploid

Question 10

What is a reticulocyte?

Answer 10

Immediate red cell precursor

Results in polychromasia

Question 11

What is a myelocyte?

Answer 11

Nucleated precursor between neutrophils and blasts

Question 12

What do all progenitors originally come from?

Answer 12

Hematopoietic stem cells

Question 13

What is self renewal?

Answer 13

A property of stem cells; lost in descendent

Question 14

What is proliferation?

Answer 14

Increase in cell numbers

Question 15

What is differentiation?

Answer 15

Descendants commit to one of more lineages

Question 16

What is maturation?

Answer 16

Descendens acquire functional properties and my stop proliferation

Question 17

What is apoptosis?

Answer 17

Descendents undergo cell death

Question 18

What are the sites of hematopoiesis in the foetus?

Answer 18

Mesoderm

Circulating progenitors detectable as early as week 5

Question 19

What is the first site of erythroid activity?

Answer 19

Yolk sac

Question 20

At what point does the liver begin production of haempoiesis?

Answer 20

Week 6

Question 21

At what pooint does the bone marrow begin haemopoiesis?

Answer 21

Week 16

Question 22

Where does hematopoiesis occur in adults?

Answer 22

Marrow within axial skeleton, pelvis and proximal long bones

Question 23

What is a bone marrow biopsy?

Answer 23

Mobilising stem cells from marrow into blood for collection and transportation

Question 24

What is the bone marrow?

Answer 24

Complex organ surrounded by a shell of bone with a neurovascular supply

Question 25

What are the components of the bone marrow under a microscope?

Answer 25

Haemopoietic cells Non-haemopoietic cells; adipocytes, fibroblasts, osteoclasts, osteoblasts Connective tissue matrix Vascular elements

Question 26

What are the venous sinuses within the bone marrow?

Answer 26

Nutrient artery and periosteal network | Arterioles drain into sinuses; wide venous vessels which open into larger central sinuses

Question 27

What is the difference between capillaries and sinuses?

Answer 27

Sinuses are larger and have a discontinuous basement membrane

Question 28

How do mature cells from the marrow enter the circulation?

Answer 28

Formed blood cells can pass through fenestrations in endothelial cells to enter the circulation

Question 29

What is the release of red cells from the marrow associated with?

Answer 29

Sinusoidal dilation and increased blood flow

Question 30

How are neutrophils released from the marrow?

Answer 30

Actively migrate towards the sinusoid

Question 31

How do megakaryocytes release platelets into the circulation?

Answer 31

Extend long branching processes called proplatelets into the sinusoidal blood vessels

Question 32

What is the difference between red and yellow marrow?

Answer 32

Red (haemopoietically active) vs yellow (fatty inactive)

Question 33

How does the ratio of red to yellow marrow change with age?

Answer 33

Increase in yellow marrow with age; results in reduction in marrow cellularity in older individuals

Question 34

What is the myeloid; erythroid ratio?

Answer 34

Relationship between neutrophils and red cell precursors (changes from 1.5:1 go 3.3:1)

Question 35

Can the myeloid:erythroid ratio change?

Answer 35

Yes; can reverse in haemolysis as a compensatory response

Question 36

How is haemopoiesis regulated?

Answer 36

Intrinsic properties of cells (stem cells vs progenitor cells vs mature cells) Signals from immediate surroundings = microenvironmental factors Specific anatomical area for optimal developmental signals

Question 37

What regulates neutrophil maturation?

Answer 37

G-CSF (granulocyte colony stimulating factor)

Question 38

What regulates thrombopoiesis?

Answer 38

Thrombopoietin regulates growth and development of megakaryocytes from precursors

Question 39

What is the "niche" of hematopoietic stem cells that provides signals for expansion, differentiation or domancy?

Answer 39

Around vasculature (arteriole or sinusoid) and provides access to different signals (cytokines)

Question 40

Can the "niche" be altered?

Answer 40

Yes; in diseased states or with therapy

Question 41

How is haemopoiesis assessed (non-lymphoid mature cells)?

Answer 41

Blood count Cell indices Morphology Bone marrow exam

Question 42

How are non-lymphoid cells assessed?

Answer 42

Blood count/ morphological assessment

Question 43

What is the use of immunophenotyping in hematopoiesis assessment?

Answer 43

Study of antigen expression; expression of antigens indicating lineage or state of development often required for lymphoid cells

Question 44

What is immunophenotyping?

Answer 44

Identifies patterns of antigen expression unique to a cell lineage Uses antibodies in combination specific to different antigens

Question 45

What is the most appropriate technique to assign cell lineage?

Answer 45

Immunophenotyping