Hematology: Origins of Blood Cells Flashcards Preview

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Flashcards in Hematology: Origins of Blood Cells Deck (19):

Hematopoietic tissue

in embryo: yolk sac

in fetus: liver and spleen

in adult: bone marrow; liver and spleen can make blood cells if needed= extra-medullary hematopoiesis (EMH)


Young marrow vs. older marrow

Young= red, active marrow

young animal produces high numbers of blood cells.

older= yellow marrow in middle, with fat and supporting cells. network of reticular cells. 

red marrow still exists at ends of long bones and flat bones


Broad overview of commitment of cell lines

Multipotent stem cell--> primitive progenitor cells CMP or CLP

CMP--> committed precursor cells MEP and GM

MEP (erythroid line): platelets and RBCS

GM: monocytes, neutrophils, eosiniphils and basophils

CLP--> committed precursors TNK and BCP

TNK: T-cells and natural killer  cels

BCP: B-cells. 



Bone marrow: (proliferating mitotic pool) multipotent stem cell-->unipotential stem cell--> rubriblast/proerythroblast-->prorubricyte/basophilic erythroblast/early normoblast--> rubricyte/polychromatophilic erythroblast

Post-mitotic pool: -->metarubricyte/orthocromatic erythroblast/late normoblast--> reticulocyte-->

in blood: erythrocyte

First recognizable cells: rubriblast/proerythroblast- first cell we can see on a microscope. blue nucleus. nucleus starts to get small and darker.

Normoblast/metarubricyte: shiny black nucleus, can see it poking out of side of cell. 


Reticulocyte and normoblast appearances

Normoblast: dark nucleus poking out of side of cell

Reticulocyte: on new methylene blue stain: supervital stain taken up-- dotted blue throughout cell. 




Life of an erthyrocyte

Bone marrow: 3-5d

Reticulocute: maturation in blood for 2 days

Mature RBC: 100 day life span

Aged/damaged rbcs to SPLEEN, liver and BM by macrophages. 

Spleen recycles iron and bilirubin and protein; iron to bone marrow and bilirubin to liver. 

Bilirubin transported to liver by albumin and liver conjugates it to make it water souble; removed in bile. 

Splenic sequestration: horses and some dogs- when stressed, can show up as a transient erythrocytosis- normalizes after 30 mins. 



RBC life span in circulation: species differences

Dog: 120 days

Horse: 145 days

Cat: 70 days

Cow: 130 days

Mice: 43 days 



Hormone produced by kidney

disease of kidney affect ability to produce EPO: chronic renal failure-->less able to produce EPO--> unable to replace RBCs

Stimulates proliferation of erythroid progenitors (precursors)

Fundamental stimulus to EPO production is hypoxia--> if levels of O2 in blood decrease, kidney stimulates EPO production, increased blood cell production. 


Granulopoiesis-white cells

Bone marrow: multipotential stem cell-->unipotential stem cell-->myeloblast

Myeloblast=first recognizable cells. Big, pinky nucleus; nucleoli, light blue cytoplasm

Myeloblast-->promyelocyte (pink granules)-->myelocyte-->metamyelocyte

Maturational post mitotic pool: metamyelocyte (bean-shaped nucleus)--> band neutrophils (horseshoe shaped nucleus)-->mature neutrophils/segmenters (storage pool). 


Life of a neutrophil

6 days to get produced in bone marrow

circulating neutrophil--> marginating neutrophil--> tissues (7-14 hours)

Once in tissues, lost from body surfaces or destroyed by macrophages.

N'phils in 2 pools: 

circulating: central column of blood- that's what we see when we take a blood sample

marginating: creep along blood vessel walls looking for damage triggers (receptors, CKs); squeeze through walls and into tissues. 

No re-entry into circulation occurs after emigration into tissue. 


Lives of other leukocytes

eosinophils: take 2-6 days to develop in BM--> 1-24 hours in circulation--> exit to tissue (skin, GI, resp)--> last for 2d to 2weeks

Monocytes: have short transit time in blood-->recruited into tissue where the differentiate into macrophages (lifespan is variable)


Lymphocyte kinetics

lymphocytes-lymphopoiesis occurs in BM (B-cells) or thymus (T-cells) 

can keep reycling lymphocytes. 


Species differences

Red cell size: dogs>horses>cats>ruminants

No release of immature red cells (reticulocytes) from BM in horses, even when they're anemic. Need to take serial samples in monitoring anemia.

Rouleaux formation: in horses (normal), in cats, sign of inflammation. Negative charge prevents RBCs from sticking. With increased blood viscosity, RBCs stack. In cat inflammation, lots of globulin-->viscous blood.

Breed differences: healthy greyhounds have an increased number of RBCS, greater than other breeds. 

Age: very young animals tend to have lower RBCs than mature adult

Seals have HUGE rbcs, llamas have bery small and elliptical rbs.

with immune-mediated destruction of RBCs, almost impossible to tell difference between a spherocyte and a small RBC. 


Cat RBCs and WBCs

eosinophils: more rod shaped granules

basophil: don't see many in dogs and cats, but sometimes looks like nucleus has holes in it

RBC: less obvious areas of central pallor 


Cow blood

v. small RBCs

lymphocytes: quite large in circulation


Horse blood

Rouleaux formation

eosinophil looks like a raspberry


Rabbit blood

tend to see more reticulocytes in lagomorphs and rodents (healthy) likely due to shorter lifespan of RBCs. 



Reptile and fish blood

reptile (lizard): n'phil equivalent=heterophil. have staining granules

platelets= ragged cytoplasmic edges

nucleated rbcs

fish: nucleated rbcs. 


Hematology values

RBC: erythrocyte concentration

Hb: hemoglobin

HCT: hematocrit= PCV (packed cell volume): volume percentage of RBCs in blood

MCV: mean cell volume

MCHC: mean cellular hemoglobin concentration

RDW: red cell distribution width (don't often look at this)

WBC: leukocyte concentration

PLT: platelet concentration

Normoblasts: nucleated red blood cells.