Bone Marrow

Question 1

What are the three categories of the stromal compartment?

Answer 1

Mesenchymal stem cells, Haemopoietic stem cells, Endothelial-like cells

Mesenchymal stem cells give rise to osteoblasts, adipocytes, and fibroblasts. Haemopoietic stem cells include monocyte-macrophages and osteoclasts.

Question 2

What is the most common site for bone marrow aspiration?

Answer 2

Posterior superior iliac crest/spine

Other sites include anterior superior iliac crest, sternum, and tibia in infants and young children.

Question 3

What are the indications for bone marrow aspiration?

Answer 3

Diagnosis, staging of disease, therapeutic monitoring, rule out infections, rule out bone marrow infiltration

Examples include lymphoma, tuberculosis, and metastatic carcinomas.

Question 4

Fill in the blank: The function of the bone marrow includes _______.

Answer 4

Formation of blood cells, acts as a reservoir for blood cells, osteogenic function, connective tissue function

It also has reticulo-endothelial cell function.

Question 5

What are the common types of bone marrow needles?

Answer 5

Jamshidi needle, Salah bone marrow aspiration needle, Islam bone marrow needle, Klima sternal needle, Watherfield iliac crest needle

Question 6

True or False: Yellow bone marrow is actively involved in the formation of blood cells.

Answer 6

False

Yellow marrow consists primarily of fat cells and is not actively engaged in blood cell formation.

Question 7

What is the primary type of hematopoietic tissue found in red bone marrow?

Answer 7

Haematopoietic stem cells (HSC)

Red marrow is composed of blood vessels, fat cells, and a large number of mature, immature, and primitive haematopoietic cells.

Question 8

What are the major types of bone marrow?

Answer 8

Red marrow, yellow marrow

Question 9

What is the role of mesenchymal cells in the bone marrow?

Answer 9

They form the cellular stroma and lay down a rich carpet of extracellular matrix proteins

Examples include proteoglycans, hyaluronate, and collagens.

Question 10

What are haematopoietic growth factors?

Answer 10

Cytokines that affect self-renewal, differentiation, and adhesion of HSCs and HPCs

Examples include stem cell factor, granulocyte colony-stimulating factor, erythropoietin.

Question 11

What cell surface markers can be used to identify haematopoietic stem cells (HSC)?

Answer 11

CD34+, CD38-, CD90+, CD45R-

Question 12

Fill in the blank: Fat cells replace haemopoietic cells in the bones of the hand, feet, legs, and arms, leading to the formation of _______.

Answer 12

Yellow marrow

Question 13

What are the dominant anatomical sites of haemopoiesis during early development?

Answer 13

Yolk sac and fetal liver

These sites contain cells with multilineage differentiation capabilities.

Question 14

What is the principal function of the non-haemopoietic cells in the bone marrow?

Answer 14

They synthesize factors that activate haematopoietic stem cells (HSCs)

These include soluble and insoluble factors.

Question 15

What is the structure of the bone marrow?

Answer 15

Hematopoietic tissue islands and adipose cells surrounded by vascular sinuses interspersed within a meshwork of trabecular bone.

Question 16

What is the composition of the bone marrow?

Answer 16

Haemopoietic cells, marrow adipose tissue, supportive stromal cells

It is a soft, gelatinous, highly vascular, and flexible connective tissue.

Question 17

What factors contribute to the fate of haematopoietic stem cells?

Answer 17

Non-haemopoietic cells

These cells play an important role in regulating HSCs through various factors.

Question 18

What are the components of the normal bone marrow?

Answer 18

Bone stroma, haematopoietic tissue, other cells

Haematopoietic tissue includes erythroid, granulocytic, megakaryocytic cells.

Question 19

What is the blood supply to the bone marrow composed of?

Answer 19

Periosteal artery, central vein, nutrient artery, periosteal capillaries, bone marrow sinuses.

Question 20

What happens to yellow marrow in cases of prolonged demand for blood cell production?

Answer 20

It can revert to haemopoietically active marrow.

Question 21

True or False: A common function of the bone marrow is serving as a reservoir for blood cells.

Answer 21

True

Question 22

What are the main sources of blood supply to the bone?

Answer 22

Nutrient artery and periosteal capillaries

The nutrient artery is the primary source, entering the nutrient canal of the bone.

Question 23

What is the function of the nutrient artery in the bone?

Answer 23

It bifurcates into ascending and descending medullary arteries, supplying blood to the inner cortex

Radial branches travel towards the inner face of the cortex.

Question 24

What type of network do cortical capillaries form after reentering the marrow cavity?

Answer 24

Sinusoidal network

This network is involved in the blood flow within the bone marrow.

Question 25

How does blood flow in the bone marrow compare to other organs?

Answer 25

It is analogous to that in the spleen and kidney ## Footnote This highlights the unique vascular structure of the bone marrow.

Question 26

What does the marrow stroma consist of?

Answer 26

A network of sinuses originating from cortical capillaries ## Footnote The sinuses terminate in collecting vessels that enter systemic venous circulation.

Question 27

What is the composition of the sinus wall in the marrow?

Answer 27

Trilaminar in nature, composed of: * Luminal layer of endothelial cells * Abluminal coat of adventitial reticular cells * Thin basement membrane ## Footnote This structure supports the function of the marrow.

Question 28

Where does haemopoiesis occur within the bone marrow?

Answer 28

In the extravascular space between marrow sinuses (intersinus spaces) ## Footnote This process is regulated by cytokines and extracellular matrix components.

Question 29

What regulates vessel tone in the bone marrow?

Answer 29

Myelinated and non-myelinated nerve fibers present in periarterial sheaths ## Footnote Non-myelinated fibers also terminate in marrow spaces.

Question 30

What is the neuroreticular complex?

Answer 30

An anatomical unit consisting of efferent nerve and marrow stromal cells connected by gap junctions ## Footnote This complex facilitates communication between sympathetic nerves and marrow elements.

Question 31

True or False: The endothelial and adventitial cells are sources of haemopoietic cytokines.

Answer 31

True ## Footnote These cells play a critical role in regulating blood cell formation.

Question 32

Fill in the blank: The sinus wall has a thin _______ membrane present between the cell layers.

Answer 32

basement ## Footnote This membrane is underdeveloped and contributes to the trilaminar structure.