Bone Marrow

4%

how much of our body weight is comprised of bone marrow?

all bones

where can bone marrow be found in infants?

only flat bones

where can bone marrow be found in adults?

• skull

• proximal end of large bones

• sternum

• ribs

• vertebrae

• iliac crest

which bones is bone marrow found in adults?

vascular sinuses

what is formed when the main artery enters and branches into periphery?

veins

what forms when sinuses combine?

reenter circulation

why do sinuses combine to form veins?

hematopoietic cords containing cells

what cells are just outside the sinuses?

through fenestrations in the lining cells of the sinus

how do cells enter the sinus after maturation?

macrophage

what are RBCs surrounding inside the sinus?

brings iron to RBCs

what is the function of macrophages in the sinus?

sinus wall

where are megakaryocytes located in the sinus?

direct entry of mature platelets

what does the location of megakaryocytes in the sinus allow?

random

what is the distribution of lymphocytes in the sinus?

stromal cells

which cells form the foundation/support?

• reticulum that extends into the marrow cords

• fat

• histocytes

• endothelial cells

what is the foundation comprised of?

50% fat; 50% tissue

how much fat and tissue is in the bone marrow?

forms bone

what is the function of osteoblasts?

destroys bone

what is the function of osteoclasts?

supplies mature cells for circulation in steady state or for increased demand

what is the function of bone marrow?

pluripotential stem cells

what is the self-renewal of cells maintained by?

the stimulus received

what determines how cells proliferate?

• colony stimulating factors

• interleukins

• erythropoietin

what are some examples of stimuli that determines cell proliferation?

• stromal cells

• fibroblasts

• endothelial cells

• macrophages

which cells produces growth factors?

only when necessary

when is a bone marrow aspirate done?

when it is required for diagnosis or treatment

when is it considered “necessary” to perform a bone marrow aspirate?

only physicians

who performs bone marrow aspirates according to many hospital?

too few red cells

what is anemia?

too many cells

what is polycythemia?

• anemia

• polycythemia

• leukopenia/unexplained leukocytosis

• immature/abnormal cells in periphery

• thrombocytopenia/thrombocytosis

• systemic disease affecting bone marrow

• heriditary diseases

what diseases affect blood production of the bone marrow?

infections that have deep seated in localized tissue

what are granulomas?

macrophage storage disease

what is gaucher?

posterior superior iliac crest

where is bone marrow aspirated in adults?

top of tibia below the knee

where is bone marrow aspirated in children and infants?

Jamshidi needle

what needle is used for bone marrow aspiration?

• dry tap

• not in bone marrow

• tumor

what are some explanations if no aspirate is collected?

reduce damage

why are coverslips used when making slides of bone marrow aspirate?

uniform cell distribution

why should you pull rather than wedge when making a coverslip?

spicule slides

what is used for a bone marrow differential count?

histology

where is the core of the bone marrow aspirate taken to?

soften bone

why is the biopsy placed in decal?

hemotoxylin-eosin

what is used to stain the biopsy?

differential

what cannot be done from a biopsy?

look for spicule/particle

how do you find a good area when looking at bone marrow on low power?

cell destruction

what does bare nuclei indicate?

megakaryocytes

what should you look for while in low power when examining a bone marrow slide?

80%

what percent of cellularity do children have?

50%

what percent of cellularity do adults between 30 and 70 have?

you subtract patient’s age from 100% to get their cellularity

how is cellularity determined in patients over 70 years old?

500-1000

how many cells are counted in a bone marrow differential?

myeloid to erythroid ratio

what do you determine when performing a bone marrow differential?

3:1

what is the normal ratio of myeloid to erythroid?

lymphs, monos, plasma cells

which cells are not included in a differential?

shorter life span

why are there more myeloid cells than erythroid cells?

the number of myeloid cells is divided by the number of erythroid cells

how is the M:E ratio determined?

>5:1

what is the M:E ratio of erythroid hypoplasia?

<3:1

what is the M:E ratio of myeloid hypoplasia?

1:1

what is the M:E ratio of erythroid hyperplasia?

>5:1

what is the M:E ratio of myeloid hyperplasia

hemosiderin

what form of iron is stored in the bone marrow?

when it is not utilizing iron properly

when is there an increase store of iron?

sideroblastic anemia

when are ringed sideroblasts observed?

pathologist

who is the only one qualified to make a diagnosis from bone marrow?