Bone Marrow Flashcards
(16 cards)
What is the first phase of hemopoiesis and when does it begin? Where does it occur?
Other stages?
mesoblastic phase, 2 weeks after fertilization; yolk sac
hepatosplenic phase, about 2nd month of gestation; spleen and liver
myeloid phase, end of 2nd trimester and continues throughout life; bone marrow
Hemopoietic tissue consists of ___ and ___.
bone marrow (myeloid tissue), lymphoid tissue
Hematopoietic stem cells differentiate from early embryonic stem cells (pluripotent cells) into two types of multipotential cells. What are they, and which blood cells do they ultimately differentiate into?
Lymphoid multipotential cells -> lymphoblasts -> B and T cells
Myeloid multipotential cells -> RBCs, megakaryocytes, the rest of the WBCs
In which stage of hematopoietic cell differentiation do morphological characteristics develop? When do they lose their potentiality? When do they lose their self-renewing capacity?
Precursor cell (blast cell) stage for all three.
In erythropoiesis, the mother cell is the ____, and the last two cell phases are ___.
Proerythroblast, reticulocyte, erythrocyte
How can early basophilic myelocytes be distinguished from early eosinophilic myelocytes or promyelocytes?
The early stage basophils have dark blue granules.
What are the stages of erythropoiesis and how can they be distinguished? When does mitosis stop occuring? When does Hb synthesis start?
Proerythroblast: large cell, loose chromatin, multiple visible nucleoli, basophilic (blue) cytoplasm
Basophilic erythroblast: (onset of Hb synth) more acidic RNA-rich cytoplasm (bluest of all hematopoietic cells), condensed nucleus, no visible nucleoli
Polychromatophilic erythroblast: cytoplasmic Hb and fewer polyribosomes creates eosinophilic and basophilic cytoplasm
-Mitosis stops-
Orthochromatophilic erythroblast: cytoplasm filled with Hb (same color as RBC cytoplasm), few polyribosomes, condensed eccentrically-located nucleus (getting ready for ejection)
Normoblast: late orthochromatophilic erythroblast
Reticulocyte: Anucleate, released to blood where maturation culminates
At which stage of erythropoiesis is the nucleus extruded?
Orthochromatophilic erythroblast -> reticulocyte (sans nucleus)
What are the stages of granulopoiesis? What are their morphological characteristics and when does mitosis stop?
Myeloblast: large round nucleus, dispersed chromatin, visible nucleoli
Promyelocyte: biggest cell, basophilic cytoplasm, azurophilic granules (lysosomes)
Myelocyte: coarse chromatin, cell-specific granules appear
-Mitosis stops-
Metamyelocyte: indented dense nucleus, granules increase in number
Band form: band/ribbon shaped nucleus (segmented), released to blood
What are the stages of monopoiesis?
Monoblast: similar to myeloblast, large nucleus, dispersed chromatin
Promonocyte: large cell, basophilic cytoplasm, indented nucleus, lacy chromatin, visible nucleoli
-Mitosis stops-
Monocyte: horseshoe/kidney-shaped nucleus
Lymphocyte progenitors initially come from ____ and migrate to the ____ where circulating lymphocytes originate.
bone marrow, thymus/peripheral lymphoid tissue
What are the two progenitors of lymphopoiesis? Where are they found? What are their characteristics?
Lymphoblast: in bone marrow, large cell, can divide 2-3 times
Prolymphocyte: smaller cell, denser chromatin, lacks surface antigens that distinguish T and B cells (they migrate to lymphoid tissues where they mature into immunocompetent cells)
What are the differences between chronic and acute leukemia?
Chronic: slow progression, proliferating cells are more differentiated (myelocytes, metamyelocytes, band cells)
“Chronic granulocytic leukemia”
Acute: rapid progression, proliferating cells are precursors (myeloblasts)
“Acute myeloblastic leukemia”
Platelets are formed from ___?
megakaryocytes
Thrombocytopenia is…
reduction in number of circulating platelets. Can cause petechia, purpura, ecchymoses
How can a proerythroblast be distinguished from a myeloblast?
The cytoplasm of a proerythroblast is slightly more basophilic (bluer).
