Hemopoiesis Flashcards
% of body weight blood and bone marrow make
Bone marrow-5 percent
Blood- 10 percent
When does hemopoiesis begin?
1-2 weeks post-conception
What is the primary site of postnatal hemopoiesis
Bone marrow
Hemopoiesis
Formation of blood cells
Myelopoiess
Production of marrow or blood cells derived from marrow
Leukopoiesis
Production of white blood cells
Erythropoiesis
Production of erythrocytes
Lymphopoiesis
Production of lymphocytes
Granulopoiesis
Production of granulocytes
Extramedullary myelopoiesis
Production of myeloid elements at sites other than bone marrow
Hemopoiesis location 1-2 weeks post-conception
Embryological site= Mesoderm of yolk sac (blood islands)
Hemopoiesis location 6 weeks of gestation to birth
First trimester=liver
Hemopoiesis location during second trimester to birth
Spleen
Hemopoiesis location third trimester of gestation throughout postnatal life
Bone marrow
What hemopoietic areas can be reactivated if needed as postnatal site of hemopoiess (extramedullary)
Liver and Spleen
What type of bone marrow is in fetus?
-Indicates
Red marrow
-active myelopoiess
What type of bone marrow is in adults?
Red marrow (flat bones, vertebrae, long bone epiphyses) -Active myelopoiesis
Yellow marrow
-Inactive myelopoiesis
Yellow marrow
- made of
- types of cells
Adipose CT
Adipocytes occupy space not needed for hemopoetic cells
T/F Yellow marrow can not be re-activated
F
It can be re-activated
How do WBC get into circulation
Central vein
Sinus of bone marrow is lined by
Endothelial cells
Stroma of bone marrow (2)
Reticular CT forms open lattice
Adventitial reticular cells (type of reticular cell)
Adventitial reticular cell fxn (5)
1-Produce and surround reticular fibers (type III collagen)
2-Prevent exposure to platelets (prevents clotting)
3-Branching of cytoplasmic processes forms scaffold for hemopoietic cells
4-Provide structural support for sinusoids
5-Differentiate into adipocytes
Bone marrow structure- sinusoids
- Structure
- Connect
- Wide, anastomotic vascular channels
- Connect branches from central artery to central vein
T/F Central artery is larger that the central vein
T
What is the benefit of the central artery being larger than the central vein?
Increases pressure in the sinusoids to prevent their collapse as cells are produced in hemopoietic tissue
Sinusoids endoethelial lining is supported by
Reticular CT and adventitial reticular cells
Where are MQ located in relation to sinusoids
Along outer wall of sinusoids and among hemopoietic cell groups
Fxn of MQ (3)
1-Eliminate old RBC, malformed cells, extruded nuclei from maturing RBC
2-Regulate differentiation of hemopoietic cells
3-Deliver Fe to developing RBC for heme formation
Pluripotential hemopoietic stem cell
- primary cell of
- What % of nucleated cells in BM
- A part of what population
- Primary cell of origin (undifferentiated) for all blood cells
- 0.1 percent
- Null cell population of peripheral blood….morphogically indistinguishable from small lymphocyte
Multipotential hemopoietic stem cells
- AKA
- Subpopulations
-CFUs (colony forming units): group of cells with a common purpose and form specific different subpopulations of cells
- Lymphocytes (CFU-Ly)
- Myeloid cells=all other blood cells (CFU-GEMM or CFU-S)
GEMM
Granulocyte
Erythrocyte
Monocyte
Megakaryocyte
What is an indicator of poietic stem cell?
CD34+ Ag
Progenitor cells
- AKA
- Fxn
Committed CFU cells or Unipotential CFU
Can form only one or two specific type of blood cells
Precursor cells
- AKA
- Fxn
AKA maturing cells
Differentiates into mature cell
T/F Some stages of development in precursor cells may be found in peripheral blood
T
Regulation of hemopoiesis (2)
Indirect control
Direct control
Indirect control of hemopoiesis
Via physiological demands to maintain homeostasis of the body
Direct control of hemopoiesis
Via growth factors and cytokines
What are pluropotential and multipotential stem cells influenced by?
- Type of control
- growth factors
- Cytokines
Direct control
- Steel factor or stem cell factor (SCF) in CM of stromal cells
- Granulocyte-MQ colony stimulating factor (GM_CSF)
- IL-1,3,6
Unpotential progenitor cells influenced by
- Control
- Growth factors
Direct control
Stem cell factor Erythropoietin Thrombopoietin GM-CSF G-CSF M-CSF
Most important growth factors and IL?
GM-CSF G-CSF M-CSF IL-1,3 6 Erythropoietin Thrombopoietin
Where did a lot of the important GF and IL originate?
MQ/monocyte
Hemopoietic cells are capable of (3)
Erythropoiesis (make RBC)
Leukopoiesis (make WBC)
Thrombopoiesis (make platelets)
Production of erythrocytes stimulated by
Erythropoietin from kidney
Erythropoietin acts on
CFU-GEMM cells to become BFU-E cells (burst forming unit)
RBC formation is coordinated to meet
2
Metabolic needs of the body
- O2 transport requirements
- Replacement of worn out RBCs
What are the general cellular changes during sequential differentiation and maturation?
- Progressive decrease in size of cell and nucleus
- Gradual condensation of nuclear chromatin and heterochromatin formation
- Polyribosome increase then progressive decrease
- Progressive hemoglobin synthesis
- Gradual loss of organelles
Give maturation stages (earliest–>most mature) of erythrocyte
Pluripotent stem cell Myeloid stem cell BFU-E CFU-E Rubriblast Prorubricyte Rubricyte Metarubricyte Reticulocyte Erythrocyte
Rubriblast
AKA
Formed from
Proerythroblast, pronormoblast
CFU-E
Rubriblast phenotype Polyribosomes Nucleuolus Golgi Transcription
Numerous polyribosomes
Nucleolus present
(-) Golgi image may be observed
Transcription of chromatin and mitosis
What gives rubriblast basophilic stain?
Polyribosomes
Prorubicyte
AKA
Formed from
basophilic erythoblast, basophilic normoblast
Rubriblast
Prorubicyte phenotype Nucleus Chromatin Polyribosomes Hemoglobin Transcription
Smaller cell and nucleus from rubriblast
Chromatin begins to condense
ABUNDANT polyribosomes (same number in more condensed area)
Hemoglobin synthesis begins but is not apparent
Transcrption of chromatin and mitosis
Rubricyte
AKA
Formed from
Polychromatic erythroblast, polychromatic normoblast
Prorubicyte
Rubricyte phenotype
Transcription
Cell and nucleus smaller than prorubricyte
Condensation of chromatin but light areas are visible in condensed chromatin
Lots of polyribosomes
Hemoglobin synthesis apparent=gray cytoplasm
CLOCK FACED NUCLEUS
Transcription of chromatin and mitosis
What stage in erythropoiesis shows apparent hemoglobin synthesis
Rubricyte
-Basophilia of ribosomes plus acidophilia of hemoglobin equal gray color of cytoplasm
Metarubricyte
AKA
Derived from
Orthochromatic erythroblast, orthochromatic normoblast
Rubricyte
Metarubricyte phenotype
- Nucleus
- Chromatin
- Polyribosomes
- Hemoglobin
- Mitosis
Small cell with PYKNOTIC NUCLEUS
Highly condensed chromatin
Small amount of polyribsosomes
Abundant hemoglobin (pinkish gray cytoplasm)
Mitosis can occur at any stage
Reticulocyte phenotype Nucleus Mitosis polyribosomes hemoglobin
No nucleus- extruded from metarubricyte
No mitosis
Few polyribosomes (slight gray tint to cytoplasm
Abundant hemoglobin
What stage of erythropoiesis can be 1% of peripheral blood in normal small animals
Reticulocyte
Reticulocyte derived from
Metaubricyte
Last stage of erythropoiesis
Erythrocyte
Erythrocyte morphology
size
organelles
Nucleus
Size and shape is variable among species
No organelles
Howell-Jolly bodies may be present (remnant of nucleus (DNA)
T/F Granulopoiesis originates from the same multipotential CFU as erythrocytes
T
T/F Progenitor cells (unipotential CFU) and early precursor cells are the same for all granulocytes
F
There are specific progenitor cells for each granulocyte
What controls what progenitor cell will become a specific granulocyte
Cytokines
What is the general trend of granulopoiesis
Decrease in cell size
Irregular nuclear shape with gradual lobation of nucleus
Synthesis of azurophilic granules
Synthesis of specific granules
What are the stages of granulopoiesis
Pluripotent stem cell Myeloid stem cell (CFU-GEMM) Myeloblast Promyelocyte Myelocyte Metamyelocyte Stab cell Granulocyte
Myeloblast
Originates from
Granules
Mitosis
Specific progenitor cell (unipotential CFU)
Cytoplasmic granules not visible
Yes to mitosis
Promyelocyte
Originates from
Granules
Mitosis
Myeloblast
Primary or azurophilic granules (lyososomes) present and visible in cytoplasm
Yes to mitosis
Metamyelocyte Originates from Granules Mitosis Nucleus
Promyelocyte
Specific granules more prominent than primary granules for granulocytes
No mitosis
Nucleus is eccentric located and less than 50 percent of invagination
Band cell Originates from Granules Mitosis Nucleus Peripheral blood
Metamyelocyte
Specific granules more prominent than primary granules for each type of granulocyte
No mitosis
Nucleus is eccentric located and MORE THAN 50 percent invagination “ribbon-like”
Can see in peripheral blood
Mature granulocyte Derived from Granules Nucleus Mitosis
Band cell
Prominent specific granules
Nucleus is multilobated and condensed chromatin
No mitosis
