What are the general functions of growth factors in hematopoiesis?
- Stimulate proliferation
- Support differentiation of maturing cells
- Enhance function of mature cells
Where does hematopoiesis take place after the yolk sac but before the bone marrow?
Mainly the liver, but also the spleen in small amounts
Stroma of red bone marrow
3D network of reticular cells and reticular fibers containing collagen type 3, fibronection, laminin, and proteoglycans
What are the main functions of red bone marrow?
- Production of blood cells
- Destruction of senescent red blood cells
- Storage of iron
What are the two groups of cells found in CFUs?
1. Multipotential lymphoid stem cells (CFU-L)
2. Multipotential myeloid stem cell (CFU-GEMM)
What lineage specific progenitors does CFU-GEMM differentiate into?
What are the first cells morphologically distinguishable as to which cell type they will become?
Precursor cells (from the lineage specific progenitor cells)
What influences the development of erythrocytes from CFU-GEMM?
- Erythropoietin (most important!)
- Granulocyte-macrophage colony stimulating factor (GM-CSF)
- Interleukin-3 (IL-3)
- Interleukin-4 (IL-4)
What occurs during erythropoiesis?
- Cell volume decreases
- Nucleus diameter decreases, chromatin condenses, nucleus is extruded
- Cytoplasm has a decreased number of polyribosomes, increased hemoglobin, and mitochondria and other organelles disappear
In what cells of erythropoiesis does mitosis occur?
It occurs in proerythroblasts, basophilic erythroblasts, and polychromatic erythroblasts
What induces CFU-GEMM to differentiate into CFU-GM and then CFU-G?
- Granulocyte colony stimulating factor (G-CSF)
What happens during the maturation of neutrophils, eosinophils, and basophils?
- Nucleus becomes more condensed and lobulated
- Cytoplasm undergoes granule synthesis
What is the first stage of granule synthesis in granulopoiesis?
The development of azurophilic granules (lysosomes)
What is the second stage of granule synthesis in granulopoiesis?
The development of specific granules (and tertiary granules in neutrophils)
What is the distinguishing factor for a Myelocyte?
Cell has developed by azurophilic and specific granules
What is the distinguishing factor for a Metamyelocyte?
Cell has more specific granules than azurophilic granules and nucleus has undergone some changes
How long do neutrophils stay in circulation? How long do they live in tissue?
- Circulatory half life of 6-8 hours
- Live about 2 days in connective tissue before undergoing apoptosis
What are the two main compartments that neutrophils pass through?
- Bone Marrow Compartments
- Vascular Compartment
Bone marrow consists of what compartments for neutrophils?
- The medullary formation compartment
- The medullary storage compartment
The medullary formation compartment
- Consists of Mitotic and Maturation Compartments
- Where cells are forming
What cell types are found in the Mitotic compartment?
What cell types are found in the Maturation compartment?
- Neutrophils in vessels, but not circulating
- Sequestered by vasoconstriction or endothelial adhesion
- Same size as neutrophils in circulation and can exchange with them
What induces monocytes to development from CFU-GEMM, then CFU-GM, and then CFU-M?
- Monocyte colony stimulating factor (M-CSF)
- Nucleus becomes polypoid due to endomitoses as the cell develops
- cytoplasm is homogeneous and intensely basophilic
What are the only two recognizable precursor stages of Lymphopoiesis?