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Flashcards in Hematopoesis Deck (46):

Average life span of RBC

120 days


Average life span of WBC

1-2 days (in bloodstream)


Name of the routine blood test taken to diagnose disease states

Complete blood count/hemogram


definition of cells based on secondary properties

CFU (colony forming unit)


Three phases of hematopoesis in embryo
two generalized phases beyond those

mesoblastic phase, hepatic phase, medullary phase
The first two are extramedullary phases (out of bone); while the third is a medullary phase


mesoblastic phase characteristics; timing

production of embryonic hemoglobin (with nucleus) and formation of blood islands in yolk sac; 2nd week


hepatic phase characteristics; timing

blood islands in liver; fetal hemoglobin in this phase (anucleated) - greater affinity for O2 than adult hemoglobin; 6th week;


why would you reactivate fetal/embryonic hematopoesis?

treatment strategy for thalassemia or sickle cell anemia


when does the spleen begin hematopoesis

2 months


medullary or myeloid phase characteristics

begins with the ossification of bone, usually around the 5th month


two types of bone marrow

red and yellow; yellow is inactive in hematopoesis and mostly adipocytes; yellow can convert to red if needed


in bone marrow failure, extramedullary hematopoesis can occur in the...

liver and spleen


lymphocyte lineage occurs where?

thymus, lymph nodes and spleen


where do you find bone marrow?

inside the bone in between trabeculae


vascular compartment in bone marrow characteristics; direction of flow

thin flat endothelial lining of sinusoids; flow from the primary nutrient artery through the diaphysis -> into venous sinuses in the marrow -> out through central venous sinus


types of cells in the extravascular compartment of bone marrow (connective tissue stroma)

reticular cells, adipocytes, macrophages, plasma cells


reticular cells (aka adventitial cells) (not reticulocytes)

production of reticular fibers that form the support matrix of the ECM and formation of growth factors


adipocyte function in bone marrow

support structure and space filler, backup source of reticular cells if demand for hematopoesis increases


macrophages in bone marrow + nurse cells (including specific functions of nurse cells)

macrophages can remove old cells from circulation;
macrophages as nurse cells can help reticulocytes to be stable as they lose their nucleus; this leads to formation of erythroblastic islands inside the bone marrow; easily destroyed during processing
specific functions include digestion of extruded nuclei and provisioning for iron, nutrients and growth factors


plasma cells

still just the source of antibodies


changes of the stroma with age

at ages 4-5 bone marrow goes from predominantly red to yellow;
around 20 the production moves from the femur and tibia to the vertebrae, sternum and ribs


how to RBC's reach the sinuosoids?

transcellular migration


types of stem cells and their characteristics

pluripotent - any embryonic tissue
multipotent - several types of embryonic tissue
committed progenitor - one type of cell


hematopoetic growth factors are called



where does erythropoetin come from? what triggers its release? what kind of cells does it cause to form?

kidney cells (liver in fetus); low oxygenation levels; CFU-E - precursors to the RBC lineage


G-CSF (what does it stand for?); when is it used? (2 times)

granulocyte colony stimulating factor; it is used when one has low neutrophil counts e.g. chemotherapy, antibiotics, anti-HIV therapy; it is also used to stimulate stem cells into the peripheral blood for BMT


what are the two types of bone marrow inspection methods available? which is preferred and why?

direct sectioning and iliac crest/sternum aspiration smear;
iliac crest/sternum aspiration smear is preferred because, when combined with Wright Giemsa stains, it reveals differences in nucleation and cytoplasm


what are the five hematopoetic lineages?

erythropoesis, granulopoesis, thrombopoesis, monopoesis, lymphopoesis


what are platelet forming cells called? what do they produce exactly? where are these activated? how many of these can they make? what are the characteristics of their nucleus?

they produce proplatelet bodies which can produce ~1200 platelets
proplatelets bodies are activated in the lungs
they can make six proplatelet bodies in their lives
their nuclei are bi-lobed because the nucleus replicates without cytokinesis


what are the histological features of erythropoesis

reduction in size
acceleration of hemoglobin production
loss of all organelles
change in cytoplasmic color from basophilic to eosinophilic due to shift from polyribosomes to hemoglobin
cytoplasmic condensation
extrusion of nucleus


erythroblastic islands form due to the influence of...

nurse cells and the microenvironment that they produce to permit RBC development


why isn't size a relevant indicator of stage of development?

because cells that have recently divided are smaller than they would otherwise appear


proerythroblast characteristics

large, round, central nucleus with basophilic cytoplasm, diffuse chromatin;
high proliferative potential


basophilic erythroblast characteriistics

nucleus condenses or fragments but cytoplasm is still basophilic;
has proliferative potential but is beginning to shut down nuclear functions


polychromatophilic erythroblast characteristics

nucleus continues to fragment;
cytoplasm now partially eosinophilic
proliferative function ceases at the end of this stage


orthochromatic erythroblast characteristics

mostly eosinophilic cytoplasm
proliferative function ceased
polyribosomes and mitochondria are eliminated
at the end of this stage the nucleus is extruded

basically a reticulocyte with a nucleus



still contains some organelles, but not many
released into bone sinusoids where they are taken up by circulation for final maturation which happens in the spleen
high concentration of reticulocytes in the blood means high levels of erythropoesis


mature erythrocytes

loss of all organelles and pumping out of water leads to assumption of characteristic biconcave shape


factors required for erythropoesis

erythropoetin; B12, folate, iron


granulopoesis is heavily influenced by...



neutrophil facts (8)

1) primary response mechanism of acute inflammatory response
2) source of pus
3) single burst of activity then death
4) active in blood stream for 6 hours, but persist in tissue for 1-2 days
5) massive reservoir in the bone marrow in case of acute injury
6) high granulocyte counts lead to accumulation of precursors
7) mediated by cytokines like IL-1, G-CSF, GM-CSF
8) very phagocytotic


stages of neutrophil production (5)

1) Promyelocyte
2) Myelocyte
3) Metamyelocyte
4) Band cell (stab cell)
5) Mature PMN


Promyelocyte characteristics (6)

1) non-circular marginated nucleus
2) blue cytoplasm (high RER content)
3) azurophilic granules (lysosomes)
4) replicative potential
5) no sub-lineage possible because of no granulation
6) distinguishable from proerythroblast by irregularly shaped nucleus


myelocyte characteristics (4)

1) accumulation of specific granules
2) ovoid nucleus
3) sub-lineage possible to ID
4) replicative potential


metamyelocyte characteristics (4)

1) ovoid/kidney shaped nucleus
2) no more replicative potential
3) clear ID of sublineages possible
4) extrusion into peripheral blood common in patients with granulocytic leukemia


Band cell (3)

1) fully mature cytoplasm
2) horseshoe shaped nucleus
3) occasionally seen in peripheral blood of healthy people