Bone Marrow Flashcards
What is the mesoblastic phase? when?
Aggregates of blood cells form in the yolk sac called blood islands. stats 2 weeks post conception
What is the hepato-splenic phase? When?
When organs start to appear. 2 months
What is the myeolid phase? When is it
Starts at the end of the second trimester and continues throughout life, RBC formation starts in bone marrow
When do leukocytes appear during gestation
8 weeks
Where does hemopoiesis occur in children
Marrow of long bones like femur and tibis
Where does hemopoiesis occur in adults
Mainly in pelvis, cranium, vertebrae and sternum
Found in cancellous bone (spongy bone)
What is yellow marrow
located in long bones and is highly inflitrated with fat, not hemopoietic but can become so if necessary
What are sinusoids in bone marrow
large vessels with thin enothelial cells around them. surrounded by reticular fibers and cells
What is the stroma in bone marrow
3D network fo adventitial/reitcular cells and reticular fibers.
everything not involved in hemtopoesis
Parenchyma
bone marrow divided into hematopoeitc compartments responsible for synthesis or RBCs and WBCs
What are adventitial cells in bone marrow
basically fibroblasts. helps divide bone marrow cavity into smaller compartments
What does a megakaryocyte make
Platelets. Largest cells you can see if marrow
Are stem cells common in bone marrow? do they have mitotic activity
Rare in bone marrow, ow mitotic activity, potentiality.
Progenitor Cells
not morphologically distinguishable, have high mitotic activity, common in marrow and lymphoid organs, mono or bi potential
What type of cells during meatopoiesis does morphologic differentiation begin
Precursor cells (blasts)
Precursor Cells are called what? mitotic acticity? how many types of cells can they become
Blasts. They are where you can start to see morphological differentiation; high mitotic activity
common in marrow and lymph
monopotentital
do Mature Cells of hematopoisis have mitotic activity
No
Which hematopoietic cells are most influenced by growth factors:
stem cells, progenitor cells, blasts (precursor), mature cells
progenitor, precursor
Which hematopoietic cells are self renewing
stem cells, progenitor cells, blasts (precursor), mature cells
Mostly stem cells, a little bit progenitor
Which hematopoietic cells have mitotic activity
stem cells, progenitor cells, blasts (precursor), mature cells
all but mature cells
What is an erythroblast? How big is it? What is th enucleous, cytoplasm like
Large, loose lacey chromatin, visible nucleoli, basophilic cytoplasm
What is formed from a proerythroblast? What is a new important feature
what is the nucleus like?
Basophilic erythroblast. onset of Hb synthesis
strongly basophilic cytoplasm, condensened nucleus, no nucleoli
What is ater a basophilic erythroblast?
Polychromatophilic ertryhoblast. the cytoplasm is full of Hb, less polyribosomes, final stage with mitosis
What is the last stage with mitosis during erythrocyte formation
Polychromatophilic ertryhoblast.
How many orthochromatiphilic erythroblasts is made from every 1 proerythroblasts
what is the nucleus like
8
condensed nucleus
What is a reticulocyte
most immature rbc released into blood and the extruded nucleus is left on the erythoblastic island
In granulopoiesis what are the mitotic cell types and which are postmitotic
mitotic: myeloblast, promyelocyte, myelocyte
postmitotic/: metamyelocyte, band form, segmented neutrophil
What features differentiate the promyelocyte from the myeloblast
Promyelocyte has basophilic cytoplasm and azurophilic granules
What features differentiate the promyelocyte from the myelocyte
In myelocyte can see more specific types of granules appearing
What features differentiate the band form from the metamyleocyte
Band form has band or ribbon shaped nucleus
What is the most immature stage cell in granulopoiesis released to blood
Band Cell
What is the last mitotic stage of monopoiesis
promonocyte
Where do circulating lymphocytes originate? what about their progenitors
Thymus and peripheral lymphoid tissue but progenitors come from bone marrow
What is the first identifiable progenitor in lymphopoesis
a lymphoblast. a large cell that can divide 2-3 times
What is a prolymphocyte
originates from lymphoblast it has more condensed chromatin and migrates to lymphoid tissue where is undergoes further matuartion to become imminocompetent (t or b antigens)
what is the difference between chronic and acute leukemia
chornic is more slowly progressing ebause the proliferating cells are partyly or completely differentiated but in acute it is rapidly proliferating because cells are undifferentiated precursor cells
What is unique about platelet formation
the megakaryoblasts replicate dna without dividing so they have big nucleus and can be up to 64n. it becomes megakaryocyte which releases platelets
What is thrombocytopenia
a severe reduction in the number of circulating platelets
-theombocytopenia purpura, petichie, echymoses,leukemia, mestastic cancers, chemo drugs
Thrombocytopenia purpura
spontaneous bleeding/ clotting defects from extremeley low platelet numbers. can get this form drugs that block megakaryocytes.
Present with petichiea, echymoses
What is petichie
pin prick bruising that may be a sign of Thrombocytopenia purpura
what is echymoses
a bruise
