lecture 11 Flashcards
during embryonic life, blood cell development occurs in many organs, what are they?
- yolk sac
- liver
- spleen
- BM
by the 9th month of fetal life, what organ is the main site of blood cell production?
BM
what are the rest cells?
- when BM becomes the main site of blood cell production, other organs (spleen,liver) will stop producing cells
- however, some cells remain in these organs (liver, spleen) known as rest cells
- rest cells can revert back to the production of blood cells if something goes wrong to the BM
blood cell formation is called:
hematopoiesis
the adjective for marrow is known as:
medullary
when blood cell formation occurs in the BM, it is known as:
medullary hematopoiesis
when blood cell formation occurs outside the BM, it is known as:
extramedullary hematopoiesis
the bone marrow is a single organ
(T/F)
true
(although BM is distributed all over the body, it can be considered as a single organ)
what is the main function of the BM?
production of blood cells
what happens when the BM fails?
- production of cells fails
- leads to many diseases
where is the BM located?
(in adults)
- fills the space between the 2 bony parts of the flat bones
- skull
- sternum
- pelvis
- spine (vertebrae)
- ribs
- proximal extremities of long bones
BM is a cellular structure
(T/F)
true
BM fills the space between 2 bony parts of long bones
(T/f)
false, flat bones
where is the BM located in children that is not found in adults?
and why?
- BM fills long bones
- because as the person grows, the marrow within long bones is replaced by fats
- so active BM remains only in flat bones
(in children BM fills all bones)
rest cells are only found in the liver and spleen
(T/F)
false, also in the long bones of adults
in children, long bones are filled with fat
(T/F)
false, adults
in an adult, how much is the total weight of the BM?
- 1 1/2 kg
- exactly the weight of the liver
what is the difference betweent the marrow structure of long bones in young persons and elderly?
- in young persons, BM is cellular
- as person grows older, blood cells become replaced by fats cells
what are the cells present in the BM?
(what is found within the BM)
- erythroid cells
- myeloid cells
- megakaryocytes
- plasma cells
- mast cells
- histiocytes
- osteoblasts
- osteoclasts
- fibroblasts
- some fat cells
the BM has a very rich blood supply and specialized vessels called:
marrow sinusoids
what do the marrow sinosoids consist of?
consist of a single lining of endothelial cells, the edges of which overlap
whatever comes out of the BM, has to first pass through:
marrow sinusoids
(from sinusoids to veins, from veins to the rest of the circulation)
examination of the BM is a widely used method for what purposes?
diagnosis of many hemtologic diseases
why is the examination of the BM, a valuable procedure?
- determines the presence of specific/ diagnostic cells found in the BM but absent from the PB
- helps us in assessing the cellularity of the BM, iron stores, distribution of different series…
when we look at the BM slide, how do we evaluate the cellularity of the BM?
we look at the cells which are between the marrow particles called spicules
what color are the cells found between the spicules? what stain?
- appear as blue masses
- wright and giemsa stain
under low power
what should be the cellularity of the BM?
normocellular (depends on the age)
what are the giant cells seen under low power in a BM slide? how are they estimated?
- megakaryocytes
- estimate their nbs (1-3/LPF)
under what power objective a differential count is made? and based on what count?
- oil immertion objective (100x)
- 500-600 nucleated cells
how much % of erythroid and myeloid cells are normally found in the BM?
what is the myeloid/erythroid ratio?
- erythroid cells 20%
- myeloid cells 80%
- myeloid/erythroid ratio (M/E ratio) is 3/1-4/1
myeloid cell age is longer than that of the erythroid cell
(T/F)
false,
erythroid cell age is longer than that of the myeloid cell
the erythroid/myeloid ratio is 3/1-4/1
(T/F)
false, myeloid/erythroid ratio
most blood cells develop from cells in the BM called:
stem cells
stem cells have 2 important characteristucs, what are they?
- ability to give rise to new stem cell (self-renewal)
- ability to differentiate into any of the blood cell lines
stem cells are morphologically identifiable
(T/F)
false, not morphologically identifiable
we cannot recognize stem cells
stems cells look very similar to:
small or intermediate lymphocytes
the earliest stem cell or the mother cell for all is a what type of stem cell
pluripotent stem cell
pluripotent stem cell gives rise to:
- B and T lymphocytes
- granulocytes
- monocytic cells
- megakaryocytes
- erythroid cells
what type of cells present in the BM is important to be able to identify them because they may be confused with other cells?
- macrophages
- mast cells
- osteoblasts
- osteoclasts
macrophages, mast cells, osteoblasts, & osteoclasts, may be confused with other cells that are:
- normal
- pathologic
macrophages, mast cells, osteoclasts, osteoblasts, are seen frequently
(T/F)
false, not seen frequently
what are plasma cells?
briefly in 2 words
tissue cells
where are plasma cells located/ found?
- plasma cells are seen wherever lymphocytes and histiocytes are found
- BM
- LN
- spleen
plasma cells are found wherever lymphocytes and macrophages are seen
(T/F)
true
macrophages = histiocytes
do plasma cells normally enter the circulation?
no
what condition do we have if plasma cells enter the circulation?
plasma cell leukemia
what is the plasma cell morphology?
what are its characteristics?
- round/oval shape
- small nucleus & eccentrically placed (to one side)
- dark bluish cytoplasm
- unstained area next to the nucleus (golgi body)
what is the plasma cell morphology?
what are its characteristics?
- round/oval shape
- small nucleus & eccentrically placed (to one side)
- dark bluish cytoplasm
- unstained area next to the nucleus (golgi body)
why do we have an unstained area next to the nucleus of a plasma cell?
due to the golgi body
plasma cells constitute how much of the BM nucleated cells?
<1%
in what conditions do we see an increase in plasma cells?
- infections
- plasma cell disorders such as multiple myeloma (highest counts)
what is the % of plasma cells in plasma cell disorders?
20% or more
what is the mast cell?
briefly in 2 words
tissue basophil
mast cells are widely distributed in the body, and normally found in the PB
(T/F)
false, not normally found
where are mast cells found in the body?
- BM
- tissues
mast cells originate from which type of stem cell?
from the same pluripotent stem cell (CD34+) as basophils
how are mast cells distributed to the tissues?
(via shu + kif shaklon)
- via blood
- as nongranulated mononuclear cells
mast cells arise from the same stem cell as basophils, and are granulated
false, nongranulated mononuclear cells
what do mast cells do in the tissues?
- continue to differentiate
- develop granules
lifespan ranging from weks to months
mast cells are similar in appearance to what type of cell?
basophils
how do mast cells differ from basophils?
- larger in size than basophils
- small round nucleus (centrally located)
- more abundant cytoplasm
- granules are unform, round & more numerous
- granules are located around the nucleus
what do the granules of a mast cell contain?
heparin and histamine
how are the granules discharged from the mast cell?
discharge granules outside the cell (exoplasmosis)
how are the granules distributed inside the nucleus?
they are located around the nucleus
mast cells may be increased in association with:
- injury to the BM because of some disease (refractory anemia, aplastic anemia)
- cancer of the lymphoid tissue involving the BM (CLL)
mast cells are rarely seen in the BM
(T/F)
true
what is the most important function of mast cells and basophils?
role in immediate hypersensitivity reactions
what is another name for macrophages?
histiocytes
macrophages are the progeny of what cells?
monocytes
what functions does the macrophage perform?
(briefly)
- phagocytic function
- immunologic function
the morphology of macrophages is always the same
(T/F)
false, differs with their locations
macrophages are the most mature cells in what system?
in the mononuclear phagocyte system
how does the macrophage appear in the BM?
(shakla + constituents)
- large cell
- d=30 micro m
- irregular (on film preparation)
- pseudopods seen
- nucleus is large, round/oval
- chromatin is spongy/ reticular in pattern
- 1 or more nulceoli
- cytoplasm abundant, light gray to blue
- contain ingested materials (RBC, WBC, platelets, microorganisms, debris)
- cytoplasmic vacuoles
- azurophulic granules
in normal marrow, macrophages comprise ____% of nucleated cells
<1%
in what conditions does the nb of macrophages increase?
disorders characterized by rapid cellular turnovers
* hemolytic anemias
* solid tumors
* leukemias
morphologically abnormal macrophages are seen in what conditions?
congenital storage diseases
* gaucher disease (most common)
* neimann-pick disease
what causes congenital storage diseases?
result from the lack of a functional enzyme required for breakdown of lipids ingested by macrophages
what causes gaucher disease?
what happens?
- enzyme deficiency (beta-glucosidase)
- causes accumulation of lipid material (glucocerobrosides) in macrophages
- resulting in characteristic cells –> gaucher cells
what causes neimann-pick disease? what happens?
- lack of sphingomyelinase
- abnormal accumulation of sphingomyelin
what do we see in the histiocyte cytoplasm in neimann-pick disease?
shows droplets of fats that stain poorly with the wright stain
gaucher cells morphology
- round/oval & small eccentric nucleus
- cytoplasm faintly blue & made of long thin empty tubes that stain lightly with wright stain (blue fibers)
what stain do we use for neimann-pick and gaucher cells?
wright stain
neimann-pick cells morphology
- baloon like
- single nucleus
- cytoplasm foamy
- full of small spherical droplets of uniform size
what are the non-hematopoietic stem cells?
- osteoblasts
- osteoclasts
what are osteoblasts?
- non-hematopoietic stem cells
- specialized cells
- synthesize new bone (bone-forming cells)
osteoblasts morphology
- oval, elongated cells
- 30 micro m in length
- nucleus round/ oval, small, eccentrically located
- sometimes nucleus seems to be partially extruded from the cell, cytoplasm streams out behind nucleus
- chromatin coarsely reticular
- 1 or more nucleoli
- basophilic cytoplasm, abundant, not smooth, grainy appearance
- granules not seen
- cytoplasmic border appears indistict
- has a rounded lighter staining area at some distance from the nucleus (golgi apparatus)
osteoblasts are confused with which type of cells?
- plasma cells
- tumor cells
how are osteoblasts similar to plasma cells? how do they differ?
similarities
* have eccentric nuclei
* basophilic cytoplasm
differences
* osteoblasts are larger, more elongated
* pale-staining area in osteoblasts is separated from the nucleus
* in plasma cells, ligher area is perinuclear
why are osteoblasts mistaken with tumor cells?
osteoblasts ofen appears in clusters and aggregates
when are osteoblasts seen on marrow films?
- in infants and children marrow (growing)
- adult marrow when active bone formation or repair is occurring (rare)
what are osteoclasts?
- nonhematopoetic stem cells
- large multinucleated cells
- involved in bone demineralization and resorption (destruction)
osteoclast morphology
- impressive size (100 micro m or >)
- about the size of a large megakaryocyte
- irregularly shaped (indistinct cytoplasmic border)
- variable nb of discrete nuclei, not connected to one another/ scattered
- nuclei round/oval
- fine reticular chromatin pattern
- 1 nucleolus seen in each nucleus
- cytoplasm ranges from cloudy light blue to light pink
- filled with azurophilic granules (irregular size, distribution)
osteoclasts may be misidentified with:
megakaryocytes
how do we distinguish osteoclasts from megakrayocytes?
briefly
examination of the nuclear structure
how do osteoclasts differ from megakaryocytes?
- in osteoclasts, each nucleus is separate, not attached
- megakaryocyte nuclei are multilobulated, superimposed
- cytoplasmic granulation in megakaryocytes is much more uniform
osteoclasts are common in all age groups
(T/F)
false,
osteoclasts common in marrow of infants & children but rarely seen in adult marrow
when are osteoclasts increased in adults?
- bone remodeling or destruction is taking place
=> osteolytic bone disease
with what conditions are osteoclasts associated with?
- osteolytic bone disease
- metastatic tumors
