Lecture 7:a.Hematopoiesis & Bone Marrow; b.Thymus Flashcards
Which organs are primary lymphoid organs (2)? What cells do they produce?
- Thymus = T cells
- Bone marrow = B cells
Which organs and tissue are secondary lymphoid organs and tissues (5)?
- Diffuse lymphatic tissue (e.g. GALT)
- Lymphatic nodules
- tonsils
- Lymph nodes
- Spleen
Where are T cells found?
Thymus
Where are B cells found?
Bone marrow and gut associated lymphatic tissues (GALT) in humans
After birth, where does hemopoiesis occur?
occurs only in red bone marrow and lymphatic tissues
Explain the 3 phases/stages of fetal hemopoiesis
- 1st phase: Embryonic yolk sac = formation of blood islands (RBCs only)
- 2nd phase:liver: red and some WBCs
- 3rd phase: Bone marrow = RBCs and WBCs, also spleen and lymphatic organs
What are the two types of bone marrow? Which one is active and inactive? What do they produce?
- Red marrow = active, produce blood cells
- Yellow marrow = inactive, produce fat cells
What makes up red marrow (3)?
- stroma (reticular cells) = produce fibers, contain fibroblasts and macrophages
- blood-forming cords (hematopoietic cord)
- endothelial-lined sinusoids (discontinuous capillaries)
Newborns have which type of bone marrow?
red
Where are lymphocytes formed?
formed in red bone marrow and in the lymphatic tissues
Explain steps of bone marrow aspiration(3)
- needle inserted into hip bone (preferred anatomical site)
- small amount of bone marrow obtained
- aspirate is spread on a glass slide
Explain steps of bone marrow core biopsy (3)
- intact bone marrow is obtained by a small incision in the skin
- biopsy needle is inserted into bone using a corkscrew movement to obtain a solid piece of bone marrow
- biopsy is used to diagnose and stage different types of cancer or monitor the results of chemotherapy
Which cells are the last cell capable of mitosis (endomitosis)?
Megakaryoblasts = chromosome replication
Under hormone stimulation by ______ causes a megakaryoblast to become a megakaryocyte (platelet-producing).
thrombopoietin
Where do platelets originate in adults?
red bone marrow by fragmentation of the cytoplasm of mature megakaryocytes
List stages of erythrocyte lineage (erythropoiesis) (6)
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- Proerythroblast
- Basophilic erythroblast
- Polychromatophilic erythroblast (last mitosis)
- Orthochromatophilic erythroblasts aka normoblast
- Reticulocyte
- Erythrocyte
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All blasts are still mitotically active and can further differentiate
RBCs develop from the multipotential ______ stem cell in bone marrow under the influence of ____ and some cytokines.
- myeloid
- erythropoietin
What are the major changes during the process of erythrocyte maturation (6)?
- Cell volume decreases
- Nucleoli diminish in size until they become invisible under LM
- Nuclear diameter decreases
- Chromatin becomes increasingly dense = thickened and reduced in size and finally extruded from the cell
- Cytoplasmic basophilia (ribosomes) decrease while acidophilia (hemoglobin) simultaneously increases
How many days does it take RBCs to develop?
7 days
How many days do RBCs circulate in the blood?
120 days
What occurs when a proerythroblast transitions to an erythrocyte (2)?
- increase in cytoplasmic hemoglobin concentration
- decrease in nuclear volume and an increase in chromatin condensation followed by extrusion of a pyknotic nucleus
Explain the process of a reticulocyte becoming a mature erythrocyte
Reticulocyte will leave the bone marrow, pass to bloodstream, lose its mitochondria and ribosomes within 1-2 days = becomes a mature erythrocyte
What are the possible pathological causes involving RBCs (4)?
- anemia
- thalassemia
- miliary tuberculosis
- cancers involving bone marrow (myelomas, leukemias, lymphomas) and chronic hypoxemia
What are the 5 stages of leukopoiesis?
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- Myeoblast
- Promyelocyte = largest cell, primary azurophilic granules only produced in this stage
- Myelocyte (neutrophilic,eosinophilic,basophilic) = primary (azurophilic) granules + secondary (specific) granules produced (1st time secondary granules are produced)
- Metamylocyte(only in neutrophils and eosinophils) = nucleus is kidney shaped
- Band cell = only in neutrophils
Mature granulocyte = 1st sign of the development of neutrophil, eosinophil, basophil
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Where are monocytes produced?
in bone marrow from a biopotential stem cell
What is aplastic anemia also called?
hypocellular bone marrow
What is Aplastic Anemia (marked w/ pancytopenia)?
reduction in the # of erythrocytes, all WBCs, and platelets in blood circulation
What causes aplastic anemia (aka hypocellular bone marrow)?
- Many cases are idopathic = unknown
- Some can follow toxic exposure to chemotherapy drugs or to chemicals such as benzene, radiation, and infection with viral hepatitis
How is aplastic anemia (aka hypocellular bone marrow) treated?
- bone marrow transplantation
- anti-lymphocyte globulin (in idopathic cases)
What is the function of the thymus?
- primary lymphatic organ
- educates thymocytes (before becoming T-cells)
What makes up the structure of the thymus?
- poorly developed capsule
- epithelioreticular cells (aka nurse cells) = responsible for development and maturation of T-cells
- few fibers
- No lymphatic nodules = no interaction with B cells
What is the function of Hassall’s corpuscle (thymic corpuscle)?
produce interleukins that function in differentiation and education of T cells
How do mature T cells (CD8+ and CD4+) leave the cortex?
through postcapillary venules in medulla and enter the blood circulation
What is DiGeorge Syndrome?
an inherited immunodeficiency disease
What causes DiGeorge Syndrome?
- the cortical epithelial (epithelioreticular) cells did not develop = thymus is underdeveloped = no T cell education b/c lack of epithelioreticular cells
What is the result of DiGeorge Syndrome?
- lack of cell-mediated immunity (low T cell count)
- loss of parathyroid gland and cardiac abnormalities
Identify the cell circled
megakaryocyte
Identify the structure that the arrow is pointing to
hemapoietic cords
Identify cell #1
megakaryocyte
Identify cell #2
adipocyte
What structure is #3 and #4?
sinusoid capillary
What cell is #1?
promyelocyte
What cell is #2?
neutrophilic myelocyte
Identify cell #4 and #5
neutrophilic metamyelocyte
Identify cell #6 and #7
orthochromatic erythroblast
Identify the cell labelled as #8
mature segmented neutrophil
Identify the cell labelled as #9
band cell (neutrophil)
Identify cell #1
eosinophilic metamyelocyte
What structure is #1?
cortex
What structure is labelled as #2?
medulla
Identify #1
orthochromatic erythroblast (aka normoblast)
Identify #2
band cell (neutrophil)
Identify #3
mature neutrophil
Identify #4
Neutrophilic metamyelocytes
Identify #5
neutrophilic metamyelocytes
Identify #6
neutrophilic myelocyte
Identify #7
neutrophilic metamyelocyte
What cell is #1 pointing to?
late polychromatic erythroblast
What cell is #2 pointing to?
eosinophilic myelocyte
What cell is #3 pointing to (blue arrow)?
late neutrophilic myelocyte
Identify #4
orthochromatic erythroblast (aka normoblast)
What cell is #5?
band cell (neutrophil)
What cell is #6?
polychromatic erythroblast
Identify cell #1
polychromatic erythroblast
Identify cell #2
late polychromatic erythroblast
Identify cell #3 (bright pink arrow)
polychromatic erythroblast
Identify cell #4
orthochromatic erythroblast
What cell is #1 (pink arrow)?
basophilic erythroblast
What cell is #2 (blue arrow) ?
promyelocyte
What cell is #3?
neutrophilic myelocyte
What cell is #4?
neutrophilic myelocyte
What type of cell is #1?
thymic (medullary) epithelioreticular cell
What structure is #2?
Hassall’s corpuscle
What cell is #3?
neutrophilic myelocyte
What cell is #4?
neutrophilic metamyelocyte
What cell is #5?
band cell (neutrophilic)
What cell is #6?
mature neutrophil
What cell is #7?
promyelocyte
What structure is #1?
capsule
What are the structures labelled as #2?
cortex
What structures are labelled as #3?
medulla
What structure is #4?
thymic corpuscle
What structure is #5?
Hassall’s corpuscle
What cell is #1?
neutrophilic series
What cell is #2?
eosinophilic myelocyte = very pink granules
What cells are #3?
myelocyte
What cell is #4?
metamyelocyte
What cell is #5?
band cell (neutrophil)
What structure is #1?
capsule
What structure is #2?
trabecula
What structure is #3?
cortex
What structure is #4?
blood vessel
What structure is #5?
- Hassall’s corpuscle
- in medulla of thymus
- unique to thymus
What is a neutrophilic myelocyte?
the first sign of the development of a specific type of granulocyte series = neutrophilic, eosinophilic, or basophilic
- Which of the following cell types is responsible for the maturation and development of thymocytes?
a. Reticulocytes
b. Epithelioreticular cells
c. Fibroblasts
d. Macrophages
b. Epithelioreticular cells
- Identify the cell:
a. Neutrophilic myelocyte
b. Basophilic erythroblast
c. Neutrophilic metamyelocyte
d. Basophilic myelocyte
c. Neutrophilic metamyelocyte
- Which of the following statements is true about the maturation of erythrocytes?
a. Decrease of cytoplasmic acidophilia & increase in cytoplasmic basophilia
b. Reduction in number of azurophilic granules & increase in nuclear volume
c. Increase of cytoplasmic RNA & decrease in cytoplasmic hemoglobin
d. Decrease in cytoplasmic RNA & increase in cytoplasmic acidophilia
d. Decrease in cytoplasmic RNA & increase in cytoplasmic acidophilia
- Which cell type, involved in the stages of erythropoiesis, marks the final stage of maturation in which the nucleus is still present?
a. Proerythroblast
b. Orthochromatophilic erythroblast
c. Polychromatic erythroblast
d. Reticulocyte
b. Orthochromatophilic erythroblast
- Which feature distinguishes myelocytes from promyelocytes?
a. Specific granules
b. Lobulated nucleus
c. Azurophilic granules
d. Basophilic cytoplasm
a. Specific granules
- Identify the cell:
a. Band neutrophil
b. Orthochromatophilic erythroblast (normoblast)
c. Basophilic erythroblast
d. Neutrophilic myelocyte
c. Basophilic erythroblast
- Identify the cell:
a. Band neutrophil
b. Orthochromatophilic erythroblast (normoblast)
c. Basophilic erythroblast
d. Neutrophilic myelocyte
b. Orthochromatophilic erythroblast (normoblast)