Chapter 7 Hematopoiesis
when does hematopoiesis begin in the bone marrow in the fetus?
5th month of development
when does hematopoiesis in the fetal liver start to decline?
6th month of development, retaining minimal activity until 1 to 2 weeks after birth.
Bone forming cells are called
osteoblasts
bone resorbing cells are called
osteoclasts
morphologic features associated with maturation:
overall decrease in cell volume and a decrease in the ratio of nucleus to cytoplasm, loss of nucleoli, condensation of nuclear chromatin, decrease in nucleus diameter
what happens after a splenectomy?
platelet and leukocyte counts increase
culling
process where cells are phagocytized with subsequent degradation of cell organelles
pitting
process where splenic macrophages remove inclusions or damaged surface membranes from circulating RBCs
Hematopoiesis
production of blood cells
Erythropoiesis
production of erythrocytes in the bone marrow
Megakaryopoiesis
production of platelets
Leukopoiesis
production of white blood cells
Common myloid progenitor
proliferate and differentiates into granulocytic, erythrocytic, monocytic, and megakaryocytic lineages
common lymphoid progenitor
proliferates and differentiates into t, b, and natural killer lymphocyte and dendritic lineages
the largest lymphoid organ in the body:
spleen
which organ filters the circulating blood?
spleen
which organ serves as a storage site for platelets?
spleen
secondary lymphoid tissue consists of:
spleen, lymph nodes, mucosa associated lymphoid tissue
which cells play a critical role in the regulation of hematopoietic stem and progenitor cell survival and differentiation
stromal cells
instructive model
The microenvironment in the bone marrow determines whether the HSC will self-renew or differentiate
hematopoietic stem cells produce all lineages of blood cells in sufficient quantities over the lifetime of an individual because they:
How the ability of self-renewable by asymmetric division
primary lymphoid tissue consists of:
The bone marrow and thymus
endothelial cells:
broad flat cells that form a single continuous layer along the inner surface of the arteries, veins, and vascular sinuses.
BFU-E
burst forming unit erythroid, earliest identifiable colony of RBCs. resemble cluster of grapes containing brightly colored hemoglobin
when does the bone marrow become the primary site of hematopoiesis?
by the end of 24 weeks gestation
undifferentiated HSC's
can differentiate into progenitor cells committed to either lymphoid or myeloid lineages
Interleukins are
cytokines
Interleukins have synergistic interactions with other:
cytokines
what does red marrow contain?
developing blood cells and their progenitors
stromal cells in bone marrow
endothelial cells, adipocytes, macrophages and lymphocytes, osteoblasts, osteoclasts and reticular adventitial cells
splenomegaly
enlargement of the spleen
GM-CSF
induces expression of genes that stimulate HSC differentiation to the common myeloid progenitor
adentitis
infection of the lymph node
inner region of lymph nodes:
medulla
Interleukins exhibit:
multiple biologic activities, such as regulation of autoimmune and inflammatory reactions and hematopoiesis
germinal centers
nodes and nodules have sites for rapidly dividing B cells and plasma cells
the nutrient and oxygen requirements of the marrow are supplied by the:
nutrient and periosteal arteries
How does yolksack hematopoiesis differ from fetal and adult hematopoiesis?
occurs intervascularly (within developing blood vessels)
asymmetric division
one daughter cell returns to the stem cell pool and the other daughter cell undergoes differentiation or apoptosis
Paracortex
t cell rich area of the lymph node
which one of the following cells is a product of the CLP?
t lymphocyte
stochastic model
theory that hematopoiesis is a random process whereby the HSC randomly commits to self-renewal or differentiation
where is the site of major t cell production in the fetus?
thymus
red pulp of the spleen contains:
vascular sinuses separated by cords of reticular cell mesh work
when does hepatic phase of hematopoiesis begin?
5 to 7 gestational weeks
adipocytes become more abundant between what ages?
5 to 7 years of age
CD7 is seen on:
T-lymphoid progenitor and natural killer cells
normal mitotic index
1%-2%
EPO serves to:
1. recruit CFU-E from the more primitive BFU-E compartment 2. Prevents apoptosis of erythroid progenitors 3. induces hemoglobin synthesis
HSC's are directed to one of three possible fates:
1. self-renewal 2. differentiation 3. apoptosis
three main functions of the lymph nodes:
1. site of lymphocyte proliferation from the germinal centers 2. involved in the initiation of immune response to foreign antigens 3. filter particulate matter, debris, and bacteria entering the lymph node via the lymph
what is the lifespan of red blood cells?
120 days
when does hematopoiesis begin in embryonic development?
19th day after fertilization
HSC's exist in the marrow in the ratio of:
1:1000 nucleated blood cells
when does hematopoiesis in the fetal liver reach its peak?
3rd month of fetal development
Monophyletic Theory
All blood cells arise from a common stem cell
CD19 is seen on:
B-lymphoid progenitors
Porphyria's:
Disorders associated with heme synthesis
what growth factor is produced in the kidneys and is used to treat anemia associated with kidney disease
EPO
which one of the following cytokines is required very early in the differentiation of a hematopoietic stem cell?
FLT3 ligand
T/F CSF (colony stimulating factor) only stimulates one type of cell lineage
False. CSF may show specificity for one cell lineage, but is capable of influencing other cell lineages as well.
Thymus
Gland in the thoracic cavity above the heart where T lymphocytes mature.
symmetric division
HSC dividing into two identical daughter cells that follow the path of differentiation
These cells are macrophages that remove senescent cells and foreign debris from the blood that circulates through the liver:
Kupffer cells
T/F One HSC is able to reconstitute the entire hematopoietic system of a lethally irridated host
True
T/F yellow marrow is capable of reverting back to active marrow in cases of increased demand on the bone marrow, such as an excessive blood loss or hemolysis.
True
Stem Cell Theory
a series of experiments conducted by Till and McCulloch in 1961
what does yellow marrow contain?
adipocytes, undifferentiated mesenchymal cells, macrophages
Kit Ligand (Stem Cell Factor)
binding of kit ligand to the kit receptor triggers cytoplasmic domain to induce signals sent to the nucleus of the HSC, stimulating the cell to proliferate
marginal zone of the spleen contains:
blood vessels, macrophages, memory B cells, and CD 4 + t cells
where does hematopoiesis take place in adults?
bone marrow
where is hematopoietic tissue located in adults?
bone marrow, lymph nodes, spleen, liver, thymus
red marrow
composed of the hematopoic cells and macrophages arranged in extravascular cords
IL-3
controls production, differentiation, and function of granulocytes and macrophages
outer region of lymph nodes:
cortex
when a patient has severe anemia and the bone marrow is unable to effectively produce red blood cells to meet the increase demand, one of the body's responses is:
extramedullary hematopoiesis in the liver and spleen
is hepatic hematopoeisis intravascular or extravascular?
extravascular
group of glycoproteins that regulate the proliferation, differentiation, and maturation of hematopoietic precursor cells
hematopoetic growth factors
How does hematopoiesis progress in fetal development?
hematopoiesis starts in the yolk sac, progresses to the AGM region, then to the fetal liver and finally resides in the bone marrow.
what plays an important role in nurturing and protecting HSCs
hematopoietic inductive microenvironment
what cells are arranged in radiating plates emanating from a central vein?
hepatocytes
thymus medulla
holding zone for mature T cells
the best source of active bone marrow for me 20-year-old would be:
iliac crest
where is the site of B cell production in the fetus?
kidney and spleen
non-development of the thymus during gestation results in:
lack of formation of t lymphocytes
medullary cords
lie interior of the lymph node and consist primarily of plasma cells and B cells
A small amount of EPO is produced by the:
liver
where is the major site of hematopoiesis during the second trimester of fetal life?
liver
Interleukins (cytokines) are effective at ____ concentrations
low
Lymph fluid is characterized by:
low protein concentration and the absence of RBCs
white pulp of the spleen contains:
lymphocytes, macrophages, and dendritic cells
EPO is a lineage-specific glycoprotein produced in the:
renal peritubular interstitial cells
