Haematopoiesis of the bone marrow

Question 1

Define haematopoesis

Answer 1

• production of cellular elements of the blood

- haematopeitic cells derived from hematopoietic stem cells (HSC)

Question 2

2 characteristics of ahematopoetic stem cells

Answer 2

1. reproduce themselves - self renewal

2. differentiate to form mature blood cells

Question 3

where does haematopoiesis occur

Answer 3

in haematopoetic niche, containing:

• soluble cytokines (growth factors)
• cell-cell-contacts
• insoluble extracell. material (produce ECM)
• all are important for development of HSC

Question 4

role of the haematopoetic niche

Answer 4

• Regulate survival, self renewal, migration & differentiation of HSC

Question 5

3 sub populations of HSC

Answer 5

1. Long-term repopulating > renewal
2. Short-term “ > Differentiation
3. Multi-potential “ > differentiation

Question 6

Stages of erythropoiesis (when using Romanowsky stain) (6)

Answer 6

1. Pronormoblast
2. Basophilic normoblast
3. Polychromatophilic normoblast (basophilic nuclei)
4. Orthochromatic normoblast (basophilic nuclei)
5. Polychromatophilic erythrocyte (anuclear)
6. Mature red blood cells (anuclear)

Question 7

how does a orthochromic normoblast lose it’s nucleus & form a mature RBC

Answer 7

• process mediated by microtubules & actin-myosin

- split orthocrhomic normoblast => reticulocyte + pyrenocyte (nuclear material)

Question 8

Describe the stages of development of myelopoiesis leading to mature granulocytes in the peripheral blood.

Answer 8

1. Myeloblast
2. Promyelocyte: 1º granules
3. N/B/E myelocyte: 2º granules (dark staining)
4. N/B/E metamyelocyte: nucleus round
5. N/B/E band: nuclei elongated ‘sausage’
6. PMN / basophil / eosinophil: constriction of nuclei

Question 9

Stages of monocytopoesis

Answer 9

1. Monoblast
2. Promonocyte
3. Monocyte

Question 10

site & stages of platelet formation

Answer 10

1. megakaryoblast in bone marrow: Hi N:C, lrg round nuclei
2. Promegakaryocyte in bone marrow: lrg cytoplasm w/ blue granules & irregular nuclei
3. Magakaryocyte in bone marrow: blue cytoplasm w/ lobulated nuclei & platelets @ side of cytoplasm
4. Mature Platelet in peripheral blood

Question 11

Describe which cell line is affected in each hypolproliferative disorder:

a) Erythroid hypoplasia
b) myeloid hypoplasia
c) Megakaryocytic hypoplasia

Answer 11

a) Anaemia
b) Leukopenia
c) Thrombocytopenia

• if a combo of 2 cell lines = bicytopenia. If a combo of 3 = ancytopenia