Sec 2 - Bone Marrow

production of hematopoietic cells

main function of bone marrow

red bone marrow

marrow that is capable of producing blood cells

yellow bone marrow

marrow that is incapable of producing blood cells

- primarily composed of fat cells

infants and young children

most bones of the body are haematopoietically active

adults

most hematopoietic activity is found in the axial skeleton

- vertebrae, ribs, sternum

- pelvic, scapula, skull

- proximal ends of the femur & humerus

Bone

Vascular System

Hematopoietic Environment

3 structures/layers of the bone marrow

Bone

contains bone marrow

cords and sinuses

2 compartments of the bone

spongy or compact

bone can be separated into:

spongy bone

Any hematopoiesis will take place where in the red bone marrow?

Vascular System

How the cells get back into circulation

- arterial flow ends in capillary beds

- capillaries reenter marrow and fuse together to form venous sinusoids

Venous Sinusoids

where cells move into to go to the vascular system

- covered by reticulum cells

- large thin-walled structures covered with endothelial cells area

Reticulum cells

the gatekeepers of the marrow

(let stuff in/out)

controls the movement of cells into and out of the vascular system

Hematopoietic Environment

Where cell production takes place

bone marrow cords

spaces between the venous sinusoids

wedge-shaped and the hematopoietic cells within them are arranged in a specific order:

Megakaryocytes

Erythroid cells

Myeloid cells / Lymphocytes / Monocytes

Megakaryocytes

Closest to the venous sinus

platelets slough off and go to circulation (Megakaryocytes too big to go into vascular system)

Erythroid cells

Not motile; only slightly motile at reticulocyte stage

produced close to the venous sinus & are forced into the sinus by the growth of the cord

erythropoietic island

Erythroid cells surrounding a histocyte

Myeloid cells, Lymphocytes, Monocytes

Develop further from the vein

motile and capable of reaching circulation under their own power

cellular migration

the migration of cells from the bone marrow to the peripheral blood circulation

1. amount of blood flow through venous sinus

2. the deformability of the cells

3. the percentage of the venous sinus that is covered by the reticulum cells

3 factors that the flow from bone marrow to peripheral blood depend on

true

T or F:

The volume and functional capacity of the bone marrow can increase based on the need of the body

yellow bone marrow can be converted to red bone marrow when needed

In emergent situations, what happens to the yellow bone marrow?

12x the normal rate for RBCs

8x the normal rate for PLTs

4x the normal rate for WBCs

What adjustments are made for RBCs, PLTs, and WBCs in emergency situations?

Jamshidi needle & Illinois needle

2 needles used for bone marrow collection

Jamshidi needle

most common needle

used for aspirate and biopsy

Illinois needle

used for aspirate only

50%

Bone marrow cellularity of normal adults:

100%

Bone marrow cellularity of children/pts with leukemia:

20%

As a person ages, cellularity decreases about:

anterior/posterior iliac crest

Preferred and most common bone marrow collection site

Sternum

Bone marrow collection site that ONLY good for aspiration, no biopsy

Spinous process

Part of vertebrae that can be used for bone marrow collection

proximal ends of the tibia

In children, where can we do a bone marrow collection?

heparinized syringe

What type of syringe is for bone marrow aspiration?

prevents clotting

Why is a heparinized syringe used for bone marrow aspiration?

made at bedside by MLS

When performing a bone marrow aspiration, where are the slides made and by who?

Wright's stain

Iron stain

H&E stain

types of stains used on aspiration slides (3)

H&E stain

Hematoxylin and Eosin

common histopathology stain used for nuclear and cytoplasmic inclusion staining

5ml

How much aspirated bone marrow is sent to flow cytometry for testing?

Cytogenetic testing (FISH, NGS, chromosome analysis)

What other testing can be done on aspiration samples?

Sternum

What bone is NEVER used for biopsy specimen

**hint: too thin & run the risk of puncturing the heart

identifying individual cells

A bone marrow biopsy can give good information about bone marrow cellularity, but is not good for: