19+20 Flashcards
Yolk-sac phase, hepatic phase, and bone marrow phase
yolk = hematopoiesis begins week 3; formation of blood islands
hepatic = major blood forming organ in second trimester
bone marrow = begins during second trimester
main contributor after birth
hematopoiesis after birth? most to least
- vertebral and pelvis
- sternum
- ribs
- lymph nodes
- femur
- tibia
What do the pluripotent stem cells give rise too?
Myeloid stem cell and lymphoid stem cell
myeloid stem cell?
give rise too:
- proerythrocyte (RBC)
- megakaryocyte (thrombocytes)
- eosinophilic myeloblast (eosinophils)
- basophilic myeloblast (basophils)
- myeloblast (neutrophil)
- monoblast (monocytes)
lymphoid stem cell?
T lymphoblast and B lymphoblast
T-cell and B-cell
endosteal niche
found in spongy bone
used for storage of stem cells, self-renewal, and inhibition of differentiation
Vascular niche
found in bone marrow
Function:
support and promote differentiation
secrete growth factors
Yellow vs red bone marrow
Red: active hematopoiesis
yellow: fat, capillaries, reticular cells, inactive hematopoiesis
Erythropoietin / thrombopoietin / cytokines
Erythropoietin = produced by the kidney’s to increase RBC precursors
thrombopoietin = hormone from the liver to stimulate platelet formation
cytokines = stimulate proliferation
What stimulates leukocyte production?
colony-stimulating factor and interleukin
Erythropoiesis
stimulated by hypoxia
- proerythroblast
- basophilic erythoblast
- polychromatophilic erythoblast
- orthochromatophilic erythoblast
- reticulocyte
- RBC
Granulopoiesis
- myeloblasts
- promyeloblast (azurophilic granules)
- myeloblast (specific granules)
- metamyelocyte
- band (horseshoe nucleus)
- mature form
MONOCYTOPOIESIS
- monoblasts
- promonocytes
- monocytes
- once in tissue = macrophages
THROMBOPOIESIS
- megakaryoblast
- megakaryocyte
- platelets are formed from the fragments of the megakaryocyte cytoplasm
LYMPHOPOIESIS
- lymphoblasts
- prolymphocytes
from bone marrow to thymus = T-cells
remain in bone marrow = B-cells
NK cells