What is the role of the liver in hematopoiesis in a fetus?
Erythroid progenitors found there by 5-6 weeks gestation. Also myeloid/lymphoid lineage production. Later, progenitor cells populate the spleen (4th fetal month)
What structure first generates RBCs, macrophages and magakaryocytes in a developing fetus? What structures produce lymphoid and non-lymphoid stem cells at the early stages of hematopoiesis in the developing fetus?
The Yolk Sac.
The Aorta/Gonad/Mesonephros (AGM) region
What are the 3 major families of white blood cells?
Granulocytes, Lymphocytes and Monocytes
Why are the 3 cell types that are lymphocytes?
T, B and NK lymphocytes
Name the 3 cell types that are granulocytes?
Neutrophils, Basophils, and Eosinophils
What are the most common tests ordered by all physicians?
CBC and CBC-D (complete blood count and complete blood count differential)
When does hematopoiesis start in the bone marrow? When does it become the primary location?
Starts 10-11 weeks gestation. Primary location in 6th-7th month gestation.
(Hematopoiesis in liver, spleen and other embryonic tissue discontinues after birth.)
What 2 things does the bone marrow need to provide to maintain hematopoiesis?
Growth Factors and Cellular Elements
Name any 2 soluble growth factors.
Any of: SCF (stem cell growth factors), GM-CSF, G-CSF, M-CSF, IL3,5,6, EPO (from kidney) or thrombopoietin (from liver)
Where is EPO produced? There is thrombopoietin produced?
EPO from kidney, Thrombopoietin from liver
What are the 2 cytokines that suppress hematopoiesis?
TGF-beta and IFN-gamma
What are the 3 types of vascular channels in the bone marrow?
Sinuses, arteries and veins
What is the structure of the sinuses in the BM and what is their function?
Structure: Endothelial cells, underdeveloped basement membrane, and interrupted layer of adventicial reticular cells.
Function: They control the passage of hematopoietic cells from bone morrow to peripheral blood after maturation. Source of hematopoietic cytokines.
What are the main components of bone marrow? (5)
Network of vascular channels (sinuses, veins, arteries), Reticular/adventitial cells, Adipose tissue, Bone cells, Extracellular Matrix
Which components of the BM produce hematopoietic growth factors/cytokines?
Adventitial Reticular cells, adipose tissue, Bone cells (osteoblasts - secrete: HGF, M-CSF, GM-CSF, and IL1 and 6), stromal cells (produce HGF and CSF)
What does thrombopoietin promote?
Megakaryopoiesis
What does Flt-Ligand promote?
produced from Stromal cells and fibroblasts promotes expansion and differentiation of pro-B cells and dendritic cells
True or false? Hematopoietic stem cells have the capacity to differentiate into 10 different lineages?
True
True or false? HSCs (hematopoietic stem cells) have a distinctive morphology and are best characterized by their functional properties.
FALSE: HCSs ARE best characterized by their functional properties BUT do NOT have a distinctive morphology.
What is a unipotential progenitor cell?
They are committed cells produced by HSCs that can then form CFUs. The 2 main types are lymphoid and myeloid.
True or false: G-CFU cells give rise to segmented neutrophils, which come from band cells.
True.
True or false: Early megakaryocytes and monocyte blast stem cells can be seen and characterized in the normal BM.
False - it is thought that Monoblast -> promonoblast - monocyte and Megakaryoblast -> promegakaryocyte -> thrombocytes (platelets)
What can maturation arrest of myeloblasts, promyelocytes and later stages of myeloid cell differentiation cause, respectively?
Acute myeloid Lyekemia from Myeloblasts (AML), Acute promyelocytic leukemia (APL) from promyelocytes and chronic myeloid leukemia (CML) from cells in the later stages.
What is a trephine biopsy and where is it taken from?
A type of BM biopsy taken from posterior superior iliac spine. 1-2 cm.
What is fluid aspiration?
Taken after the biopsy, separate puncture, same incision, 1.0 mL.
When would you do a sternum biopsy? Would you take a core sample from the sternum?
Only done as a last resort from morbidly obese patients by an experienced physician. Never take a core sample.
Which of the following are found in peripheral blood: Megakaryocytes, myelocytes, metamyelocytes, erythroblasts and nucleated RBCs, or Bands and segmented granulocytes?
