Bone Marrow & Hemopoiesis Flashcards
Blood cells arises from?
Pluripotent hemopoietic stem cell.
what are the other sites Hemopoietic Pluripotential stem cells can be found in?
In very small numbers in sites of blood cell formation, and even smaller numbers can be found in the peripheral blood.
Histologically hemopoietic stem cells resembles what? How they could be differentiated?
They resemble lymphocytes
By immunohistochemical
techniques as they have distinctive cell-surface antigens.
Hemopoietic Stem cells gives rise to?
2 major lineages of progenitor cells
1- Lymphoid cells (lymphocytes)
2- Myeloid cells (granulocytes, monocytes, erythrocytes, and megakaryocytes).
Where does lymphoid progenitor cells migrate?
From the bone marrow to the thymus or the lymph nodes, spleen, and other lymphoid structures, where they proliferate and differentiate.
Why progenitor for blood cells are called colony forming units (CFUs)?
Because they give colonies of only one cell type when they cultured in vitro or inside the spleen
What are the types of progenitor cells/CFUs and what they form?
1- Erythroid: form the lineage of erythrocytes.
2- Thrombocytic: form the lineage of megakaryocytes for platelet formation.
3- Granulocyte-monocyte: form the lineage of all three granulocytes
and monocytes.
4- Lymphoid: form the lineage of B lymphocytes, T lymphocytes,
and natural killer cells.
what are the stages of progenitor cells lineage division?
Each progenitor cell lineage divide rapidly, producing large numbers of precursor cells (or blast) that differentiate to mature cells.
During differentiation of the stem cells to mature cells what are the changes that happens to the properities
The potentiality and capacity for self-renewal become restricted
The stem cells proliferate slowly while progenitor and precursor cell goes through more rapid mitotic activity until they become mature cell where there is no need for mitotic activity
The characteristic morphological features that shows specific functional properities start manifesting as the cells become mature
The influence of GF provide assistance for cells promoting growth and development while directing them to their destination.
What is the clinical importance of Hemopoietic growth factors?
Inc marrow cellularity and blood count in patients such as severe anemia or during chemo- or radiotherapy ( which lower white blood cell counts (leukopenia))
+
Increase the efficiency of marrow transplants by enhancing cell proliferation (so they could go together)
What are hemopoietic growth factors and what are their function?
Also called colony stimulating factors (CSF) or cytokines, are glycoproteins that stimulate proliferation of progenitor and precursor cells and promote cell
differentiation and maturation within specific lineages
What is hemopoiesis and mention the sites for it during development?
It is the replacement of mature cells by new cells from the precursors
1) occurs firsts in the mesodermal cell of embryonic yolk sac.
2) the in the liver during the second trimester.
3) In the bones during the last 2 month of gestation.
4) Bone marrow in many locations through puberty then becomes restricted to the axial skeleton.
Where is Bone Marrow found?
Medullary canals of long bones and in the small
cavities of cancellous (spongy) bone.
Mention the types of Bone marrow and state the difference b/w them?
1) Red bone marrow (blood-forming): its color is produced by the abundance of blood and hemopoietic cells.
2) Yellow bone marrow: filled with adipocytes.
What are the main structures for red bone marrow?
1- Reticular connective tissue stroma.
2- Heamopoietic cords or islands of cells.
3- Sinusoidal capillaries (Large, fenestrated, discontinuous).
4- Matrix.
