embryology: hematopoeisis Flashcards
What does hematopoiesis mean
Formation & development of blood cells
Why is hematopoiesis important
Blood cells are constantly lost/destroyed & to maintain homeostasis it must have self renewal capacity
What is the 2 steps in hematopoiesis
- Proliferation of progeny stem cells
- Differentiation & maturation of stem cell into functional cellular elements
In what two ways does fetal RBC differ from adult RBD
- Nucleus present
- HbF due to higher oxygen affinity
What is the 3 hematopoeitic waves
- Primitive hematopoiesis
- Pro-definitive hematopoiesis
- Definitive hematopoiesis
Where does primitive hematopoiesis occur
Along the wall of the yolk sac
What cells are formed in primitive hematopoiesis
Primitive erythrocytes, megakaryocytes & macrophages that remains in yolk sac or invade embryo to generate microglia
Where does pro-definitive hematopoiesis occur
Yolk sac
What cells are formed in pro-definitive hematopoiesis
Hematopoeitic progenitor cells that seeds embryo & liver
Where does definitive hematopoiesis occur
Intraembryonic in the dorsal aorta forming the endothelial to hematopoietic transition
What cells are formed in definitive hematopoiesis
Hematopoietic stem cells that seeds the liver & bone marrow
What organ replaces the yolk sac for blood cell production & when
Liver at 6-8 weeks
When does the RBC production shift to the bone marrow
Production of RBC reduce by the liver at 6 months pregnant & shifts to bone marrow
What is responsible for the liver to bone marrow RBC production shift
Cortisol
What is the function of the thymus & hormone present
Maturation of T lymphocytes into immunocompetent T cells
Thymosin hormone
