1. Hematopoiesis Flashcards
What do adventitial cells do?
Produce reticular fibers
(Create the “chicken wire” cage for cells in the bone marrow)
Secrete cytokines
What hormone regulates erythropoiesis?
Erythropoietin (EPO)
What are the official names for a maturure neutrophil?
Polymorphonuclear neutrophil
Segmented neutrophil
When might you see more reticulocytes in the blood under physiologic conditions?
During periods of increased blood production (eg, more EPO signaling)
What might cause hypocellular marrow?
Aplastic anemia
Chemotherapy
What are the two types of bone sample biopsies, and which type is better for determining cellularity?
Bone marrow aspirate and Bone marrow core biopsy
Bone marrow core biopsy maintains the structure, and is better for determining cellularity
Where do older people (older than 25, that is) have most of their hematopoiesis occur?
In the flat bones
(Ribs, Sternum, Vertebrae)
What follows an orthochromatophilic erythroblast in hematopoiesis?
What characteristic of the descendent shows this change?
Polychromatophilic erythrocyte (reticulocyte)
Almost entirely eosinophilic cells (somewhat basophilic sometimes)
Few polyribosomes
What demographic would have an increased amount of yellow bone marrow?
Older populations
What descendant of the Common Myeloid Progenitor (CMP) differentiates into dendritic cells, neutrophils, mast cells, eosinophils, and monocytes?
Granulocyte / Monocyte progenitor (CFU-GM)
What follows a basophilic erythroblast in hematopoiesis?
What characteristic of the descendent shows this change?
Polychromatophillic erythroblast
Polychromatophillic erythroblasts have some basophilic portions (polyribosomes making Hb) and some eosinophillic regions (Hb itself, stains with eosin). Also the nucleus is smaller, and you may see a checkerboard pattern to the nucleus)
What are the four common progenitors after the granulocyte / monocyte progenitor (CFU-GM) for basophils, eosinophils, and neutrophils?
Myeloblast
Promyelocyte
Myelocyte
Metamyelocyte
What two places do immature neutrophils (band cells) “hang out” waiting to respond to demand?
Reserve pool (5 days in bone marrow)
Marginated pool (stuck to endothelial walls)
What follows a polychromatophilic erythroblast in hematopoiesis?
What characteristic of the descendent shows this change?
Orthochromatophilic erythroblast (normoblast)
More acidic (eosinophilic / pink) cytoplasm
No longer capable of divison
Begin extruding nucleus
Which type of bone marrow is more hematopoietically active?
Red bone marrow
What is interesting about the division of cells that creates a megakaryocyte?
It occurs without cytokinesis, resulting in a large nucleus. This is also called “successive endomitosis.”
- Karyo- means “relating to the nucleus of a cell”*
- # Darrenfacts*
What is the Monophyletic Theory?
The theory that describes the idea that all blood cells are derived from a single pluripotent hemopoietic stem cell
What follows the monocyte progenitor cell / monoblast in monocyte development?
Promonocyte
What follows down the line to erythrocyte from a proerythroblast?
Basophilic erythroblast
What happens to make a promonocyte a monocyte?
It divides two or three more times. The last division is a monocyte.
What signaling molecules are required for monocyte development?
PU.1
Egr-1
IL-3
GM-CSF
At what stage of granulopoiesis do we start to see specificity between neutrophils, basophils, and eosinophils?
The myelocyte phase
This is where we see granules form that are specific to the granulocyte the cell intends to become. Cells will be named as such, eosinophilic myelocyte, basophilic myelocyte, etc. based on their destination.
Which type of bone marrow is 50/50 adipose and hematopoietic tissue?
Yellow Bone Marrow
What two signaling molecules stimulate basophil, eosinophil, neutrophil, and monocyte production?
IL-3
GM-CSF
Where are T lymphocytes produced, and where are they developed?
Produced in the bone marrow, develop in the thymus.
What changes ErP’s (Erythrocyte Progenitors, AKA Erythropoietin Sensitive Erythrocyte Committed Progenitors, AKA Erythrocyte Colony Forming Units) into Proerythroblasts and is therefore responsible for terminal differentiation into the erythroid lineage?
GATA-1
What two cells does the hemopoietic stem cell (the common ancestor for all blood cells) divide into?
Common Myeloid Progenitor
Common Lymphoid Progenitor
What signaling molecules are essential for initiating thrombopoiesis?
GM-CSF (granulocyte-macrophage colony stimulating factor)
IL-3
In thrombopoiesis, what follows the MKP (megakaryocyte progenitor) stage?
Megakaryoblast
What do metamyelocytes give rise to?
Banded Cells
What two signaling molecules are required for B lymphocyte development?
Ikaros
Pax5
What are the first three cellular stages in lymphopoiesis?
Hemopoietic stem cell
Common lymphoid progenitor
Pre- (T, B, Natural Killer) cell
What is the last common progenitor for erythropoiesis and thrombopoiesis?
Megakaryocyte / Erythrocyte Progenitor (MEP)
Where do fetal hematopoietic islands develop from?
Hemangioblasts
What might cause hypercellular marrow?
Leukemia :(
What three signaling molecules are responsible for the changeover from common myeloid progenitor cell to megakaryocyte-committed progenitor cells (MEPs).
EPO
IL-3
IL-4
What two signaling molecules cause the differentiation of monocytes into macrophages?
GM-CSF
M-CSF
What hormone upregulates thrombopoiesis, and where is it produced?
Thrombopoietin
Liver (primarily) and Kidneys
In thrombopoiesis, what follows the megakaryoblast stage?
The megakaryocyte itself
What two signaling molecules are required for T lymphocyte development?
Ikaros
GATA-3
At what stage does an erythroblast extrude its nucleus and become incapable of division?
At the orthochromatophilic erythroblast (normoblast) stage
When does the bone marrow become the primary site of hematopoiesis in fetal development?
The 7th month
Where does hematopoiesis occur in the 2nd trimester?
Liver and Spleen
Why do some say that neutrophils and basophils don’t have a band cell precursor?
Because their granules are so intensely staining that their band cells are impossible to differentiate.
Where does hemopoiesis begin in the first trimester?
Hematopoietic islands of the umbillical vessicle (yolk sac)
What do we call the cytoplasmic processes of the megakaryocyte that pass into the sinusoids?
Proplatelets
What does a Megakaryocyte committed Progenitor cell (MEP) divide into?
Erythropoietin sensitive erythrocyte committed progenitors
(ErP / CFU-E [Colony Forming Unit - Erythrocyte])
Megakaryocyte Progenitor
Where do young people (ages 9 to 25) have the most hematopoiesis?
In the long bones
(Tibia and Femur)
What is a general term for the descendents of Common Myeloid Progenetors (CMPs)?
Lineage-restricted progenitors
Note: This term is not used for the descendents of CLPs.
What follows a Granulocyte Monocyte Progenitor (GMP) in monocyte development?
Monocyte progenitor cell (MoP)
or
Monoblast
What do we call the change in neutrophil ratios due to high demand? (Eg: massive infection)
Left neutrophil shift
(Towards more immature neutrophils)
In thrombopoiesis, what follows the MEP stage?
Megakaryocyte Progenitor (MKP)
Which granulocyte’s band cells can you possibly identify?
Neutrophil’s
What is a sinusoid in bone marrow?
Sinusoids are unique vascular units that enter bone marrow to allow blood cells to enter circulation
How do you calculate normal cellularity (ratio of hematopoietic cells to adipocytes in bone marrow)?
100 - AGE ± 10%
Eg: age 35 = 55% - 75%
Which cell populations develop closer to the sinusoidal wall in bone marrow, and which are farther away?
Erythrocytes and Megakaryocytes develop closer to the sinusoidal wall
Granulocytes develop farther away
(Granulocytes can migrate better?)
What is a characteristic of the endothelial lining of a sinusoid that helps cells enter circulation?
The basement membrane of the endothelial lining is discontinuous
