Hematopoiesis

Question 1

Where pre-natal hematopoiesis occurs

Answer 1

• Yolk sac period: 0 months-3 months gestation, primitive blood cells (especially RBCs) produced in yolk sac
• Liver/spleen (lesser extent) period: 2 months-7 months gestation

Question 2

Where post-natal hematopoiesis occurs

Answer 2

• At birth, bone marrow is firmly established as site of hematopoiesis
• As child ages, hematopoiesis becomes more and more localized to the axial skeleton
• By age 18-20, 90% of hematopoietically active marrow is in vertebrae, pelvis, sternum, ribs and skull

Question 3

Hematopoeisis outside of the bone marrow after birth is

Answer 3

abnormal, called extramedullary hematopoiesis

Question 4

Stem cell:

Answer 4

the most primitive cell type, capable of self-renewal or differentiation/maturation

Question 5

Progenitor cell:

Answer 5

(aka: committed stem cells) limited ability to self-renew, irreversibly committed to differentiate along one or at most 2 lineages

Question 6

Precursor cell:

Answer 6

recognizable, maturing cells (ie: that is an immature neutrophil, it will become a neutrophil), capable of cell division, but CANNOT self-renew, give rise to mature, functional cells in the peripheral blood, lymphoid organs and reticuloendothelial system

Question 7

Pluripotential:

Answer 7

mother of all blood cells, gives rise to both lymphoid and myeloid elements, CFU-LM (LM=lymphoid/myeloid), can self-renew or commit to becoming a multipotential stem cell

Question 8

Multipotential:

Answer 8

CFU-GEMM (GEMM=granulocyte/erythroid/monocyte/megakaryocyte), mother of all myeloid blood cells, some ability to self-renew or they commit to becoming progenitor cells

Question 9

Myeloid progenitors:

Answer 9

• CFU-GM (granulocytes/macrophage)
• CFU-G (granulocyte),
• CFU-M (monocyte),
• CFU-E (erythroid),
• CFU-Meg (megakaryocyte),
• CFU-Eo (Eosinophil),
• CFU-Baso (Basophil),
• BFU-E (Burst forming unit, gives rise to CFU-E)