General Aspects of Haemopoiesis

Question 1

Haemopoiesis refers to

Answer 1

Blood cell formation

Question 2

Erythropoiesis refers to

Answer 2

Formation of red blood cells

Question 3

Myelopoiesis refers to

Answer 3

Formation of granulocytes and monocytes

Question 4

Thrombopoiesis refers to

Answer 4

Formation of platelets

Question 5

Definitive haemopoiesis derives from a population of stem cells first observed on the…

Answer 5

dorsal aorta termed the AGM (aorta-gonads-mesonephros) region.

Question 6

Site of haemopoiesis as a fetus:

Answer 6

0-2 months: yolk sac
3-7 months: liver and spleen
5-9 months: bone marrow

Question 7

Site of haemopoiesis of an infant:

Answer 7

Bone marrow (practically all bones)

Question 8

Site of haemopoiesis of an adult:

Answer 8

Skull, vertebrae, sternum, ribs, sacrum, pelvis, proximal ends of femur

Question 9

How does haemopoiesis start?

Answer 9

With a pluripotential stem cell that can self-renew but also give rise to separate cell lineages

Question 10

List the main characteristics of a haemopoietic stem cell

Answer 10

• Rare- 1 in 20 million nucleated cells in bone marrow
• Phenotype unknown
• CD34+ CD38- and negative for lineage markers
• appearance of a small-medium lymphocyte

Question 11

Cell differentiation occurs from the stem cell via

Answer 11

committed ‘haemopoietic progenitors’, which are restricted in their developmental potential

Question 12

What are considered to be ‘mature cells’

Answer 12

Red cells, granulocytes, monocytes, megakaryocytes and lymphocytes

Question 13

Why does bone marrow provide a suitable environment for stem cell survival, self-renewal, and formation of differentiated progenitor cells?

Answer 13

Bone Marrow is composed of stromal cells and a microvascular network.
Form an extracellular matrix and secrete several growth factors necessary for stem cell survival

Question 14

Stromal cells include:

Answer 14

• adipocytes
• fibroblasts
• osteoblasts
• endothelial cells
• macrophages

Question 15

Stromal cells form an extracellular matrix by secreting…

Answer 15

extracellular molecules such as collagen, glycoproteins and glycosaminoglycans.

Question 16

What general roles do groth factors play in haemopoiesis?

Answer 16

• stimulate proliferation of early bone marrow cells
• direct differentiation to one or other cell type
• stimulate cell maturation
• suppression of apoptosis
• functional activation

Question 17

The cell cycle (aka cell division cycle) is divided into:

Answer 17

1. Mitotic Phase (M phase): during which the cell physically divides
   (further partitioned into 2)
   
   • classical mitosis
   • cytokinesis

2. Interphase: during which the chromosomes are duplicated and cell growth occurs prior to division
(further divided into 3 main stages) 
   - G1 phase
   - S phase 
   - G2 phase