Hematopoiesis Flashcards
Romanovsky Stain
Combination of 2 basic dyes and 1 acid dye
- Basic dyes- azure B and methylene blue
- acid dye- eosin
Hematopoietic organs
Bone marrow
lymphoid organs
liver in fetus
Granulopoiesis
Development of granulocytes
- Neutrophils
- Eosinophils
- Basophils
General features of neutrophil differentiation
condensation- of nuclear chromatin
Nucleus becomes lobulated
cytoplasmic granules appear
cytoplasmic basophilia gradually decreases
Stages of neutrophil differentiation
Blast (myeloblast) neutrophilic promyelocyte neutrophilic myelocyte neutrophilic metamyelocyte neutrophilic band mature neutrophil
What 4 cells are normally found in bone marrow
blasts
promyelocytes
myelocytes
metamyelocytes
What 2 cells are found in peripheral blood
bands
adult neutrophils
Kinetics of neutrophil production
takes from 9-14 days
-most of the time spent in bone marrow
Cells leave blood vessels and enter surrounding tissues
- -diapedesis
- paracellular route
- transcellular route
Cells live for about 5 days in surrounding tissue
Marrow granulocytic reserve (MGR)
number of cells in bone marrow
Total blood granulocyte pool (TBGP)
number of granulocytes in peripheral circulation
Red bone marrow
Site of hematopoiesis -Flat bones of body sternum vertebrae ribs clavicles bones of pelvis bones of skull
Red bone marrow consists of
blood vessels
discontinuous sinusoids
cords of hematopoietic cells- site of blood cell maturation
Hematopoietic stem cell niche
interactive structural unit that nurtures and facilitates their activity
- localized supporting cells
- ECM protiens- fibronectin, laminin, agrin
- soluble factors derived from supporting cells
Found in association with spongy bone
osteoclasts
osteoblasts
endothelial cells
Osteoclasts
create spaces in bone surface
Osteoblasts
required for stem cell localization
endothelial cells
bone marrow macrophages and stromal cells involved
Yellow bone marrow
Not active in hematopoiesis location- medullary cavities of all other bones consists mostly of adipose cells -storage of reserve energy -reserve of hematopoietic tissue
Erythrocyte differentiation
Decrease in cell volume decrease in nuclear diameter increase in heterochromatin disappearance in nucleoli loss of nucleus decrease in cytoplasmic basophilia increase in cytoplasmic eosinophilia
Stages of erythrocyte differentiation
blast (erythroblast) basophilic erythroblast polychromatophilic erythroblast normoblast reticulocyte orthochromatic erythroblast mature erythrocyte
Fate of normoblasts
80% will become reticulocytes- released into circulation and can be used to estimate rate of RBC production
20% will become orthochromatic erythroblasts- not normally released into circulation
Kinetics of erythrocyte production
8-9 days
most of time spent in bone marrow
Distribution of RBCs
of circulating mature RBCs is about 20X the # of immature forms in bone marrow
ready reserve- located in red bone marrow
Erythropoietin
Glycoprotein hormone
synthesized in kidney cortex
increases rate of mitosis and RNA synthesis in developing RBCs
Hypoxia
stimulates the synthesis of erythropoietin
Conditions that can lead to hypoxia
Hemorrhage
hemolysis
high altitude
compromise of pulmonary function (emphysema)
Model of platelet production
pseudopod formation
pseudopods elongate forming proplatelets
platelets released from ends of pro platelets
demarcation channels are a membrane reservoir
T-lymphocytes
leave thymus and populate specific regions of peripheral lymphoid organs
- lymph nodes
- spleen
- tonsils
B-lymphocytes
leave bone marrow and migrate to peripheral lymphoid organs where they complete differentiation
- lymph nodes
- spleen
- tonsils
Kinetics of monocyte differentiation
formation in bone marrow takes 2-3 days
remain in peripheral circulation for 1-2days
migrate to tissues and become histiocytes
function as tissue macrophages for 1-3months
