Hematopoiesis Flashcards
Hematopoiesis before birth
First 3 months: yolk sac — embryonal stage
Remainder: liver/spleen — fetal stage; 2nd to 7th month primarily in liver and a little spleen — bone marrow should be fully established at birth
Hematopoiesis in childhood
At birth and early childhood: Most of marrow cavity is hematopoietically active
As child ages: more localized to axial skeleton
Hematopoiesis in adulthood
By 18-20 yo: 90% of activity happens in vertebrae, pelvis, sternum, ribs, skull
Primarily in vertebrae and pelvis — then sternum — then ribs
Describe hematopoietic stem cells
Two types: pluripotent and multipotent
Give rise to progenitor cells
Describe hematopoietic progenitor cells
Ability to self-renew is very limited
Irreversibly committed to differentiate along 1 (or maybe 2) lineage
Give rise to precursor cells
Describe hematopoietic precursor cells
Maturing cells that are visible and counted when marrow is examined — give rise to mature functional cells
Capable of cell division, not self-renewal
Eg: myeloblasts, myelocytes, orthochromic normoblasts
Describe pluripotent stem cells
“Mother” of all blood cells (e.g. lymphoid and myeloid)
Can self-renew or commit to becoming a multipotent cell
Describe multipotent stem cells
Two types: CFU-GEMM and CFU-L — can self-renew or differentiate to progenitor cells
CFU-GEMM: “Mother” of all non-lymphoid blood cells
CFU-L: “Mother” of all lymphoid cells
Describe erythropoietin (EPO)
Made by certain kidney cells in response to hypoxia
Promotes erythropoiesis
Describe thrombopoietin (TPO)
Promotes megakaryopoiesis
Describe granulocyte-monocyte colony stimulating factor (GM-CSF)
Promotes granulopoiesis and monopoiesis
Describe granulocyte colony stimulating factor (G-CSF)
Promotes granulopoiesis
Describe monocyte colony stimulating factor (M-CSF)
Promotes monopoiesis
Describe interleukin-5 (IL-5)
Promotes eosinophil production
Describe interleukin-3 (IL-3)
Promotes basophil production
