Bone Marrow and Hematopoiesis

Question 1

Contrary to as in other cell types, in blood precursor cells the nucleolus stains _____.

Answer 1

Pale

Question 2

How does the nucleus appear in an immature cell?

Answer 2

Larger and more pale

Question 3

What does it mean if a nucleus is pyknotic?

Answer 3

It is very dense with chromatin/made up entirely of heterochromatin. Appears this way shortly before extrusion in maturing blood cells

Question 4

How does the nucleus mature during blood cell maturation?

Answer 4

Condenses, gets smaller, eventually is extruded (RBCs) or segmented (granulocytes)

Question 5

How does cytoplasm change in maturing erythrocytes?

Answer 5

Cytoplasm is basophilic in immature erythrocytes and becomes increasingly eosinophilic as hemoglobin accumulates/ribosomes degrade.

Question 6

The _____ granules stain the same color as the nucleus in the _____ stain.

Answer 6

azurophilic, Wright stain

Question 7

Azurophilic granules are ______ granules. Describe their size.

Answer 7

Primary. Tend to be smaller and more variable in size.

Question 8

Eosinophilic granules are _____ granules. Describe them.

Answer 8

Secondary. Tend to be larger and rounder and more uniform than primary granules.

Question 9

Passage between marrow and stromal tissue is mediated by ______ cells.

Answer 9

Endothelial

Question 10

Red marrow is composed mostly of ____ cells.

Answer 10

Parenchymal

Question 11

Yellow marrow is composed mostly of _____ cells.

Answer 11

Fat

Question 12

Is the conversion from red to yellow marrow reversible?

Answer 12

Yes, if a need for more blood-forming capacity arises

Question 13

What is the role of marrow adipocytes?

Answer 13

Controlling osteogenesis and vascular growth through growth factors and other chemokines.

Question 14

What are marrow cells of mesenchymal origin?

Answer 14

Osteoblast, fibroblast, endothelial, mesenchymal stem cell

Question 15

Where are osteoblasts found and what do they do?

Answer 15

Found at the margins of marrow space.

Secrete collagen and a variety of glycoproteins to produce new bone matrix.

Maintain hematopoietic microenvironment.

Question 16

What do fibroblasts do?

Answer 16

Secrete components of the ECM and produce colony stimulating factors that act on progenitor cells.

Usually are the most closely apposed stromal cells to hematopoietic cells.

Question 17

What does the endothelial cell do?

Answer 17

Form the vascular lining and controls passage of cells between marrow and general circulation, primarily through expression of adhesion molecule (e.g. CD34)

Question 18

What do mesenchymal stem cells do?

Answer 18

Differentiate into adipocytes, osteoblasts, and other non-hematopoietic stromal cells. Produce cytokines and regulate microenvironment.

Question 19

What are the stromal cells of hematopoietic origin?

Answer 19

Macrophages, osteoclasts, connective tissue fibers, blood supply

Question 20

What do macrophages do?

Answer 20

Phagocytose senescent cell and particulate debris.

Secrete cytokines that maintain and encourage the development of surrounding hematopoietic cells.

Question 21

What cells are the progeny of CFU-GM progenitor cells?

Answer 21

Macrophages

Osteoclasts

Question 22

Where does the osteoclast reside and what does it do?

Answer 22

Resides in the margins of the marrow.

Resorbs bone

Question 23

What are sinusoids?

Answer 23

Flattened endothelial cells that have little or no basement membrane. Created by capillaries.

Question 24

By week ___ the fetal circulation system is established.

Answer 24

5

Question 25

Hematopoietic precursors are first observed in the ____ and ____ week of gestation.

Answer 25

3rd and 4th

Question 26

When does blood cell production begin in the marrow?

Answer 26

5th month of gestation

Question 27

By age 25, red marrow is confined to where?

Answer 27

Proximal quarters of the long bones, the skull, bones, ribs, sternums, scapulae, pelvis, etc.

Question 28

In adulthood, hematopoietically active bone is confined to what kind of bone?

Answer 28

Cancellous

Question 29

What daughter cells do pluripotent hematopoietic stem cells (PHSCs) give rise to?

Answer 29

CMP (common myeloid progenitor) and CLP (common lymphoid progenitor)

Question 30

What are progenitor cells?

Answer 30

Cells capable of self-renewal but are committed to one cell line. Often referred to as colony forming units.

Question 31

What factors influence differentiation of hematopoietic stem cells?

Answer 31

Colony stimulating factors (CSFs) Interleukins Erythropoietin (RBCs) Thrombopoietin (platelets)

Question 32

What is a precursor cell?

Answer 32

A cell that can only divide into a further differentiated cell and CANNOT renew itself.

Question 33

What organ monitors/controls the amount of circulating RBCs?

Answer 33

Kidneys. They make the cytokine erythropoietin in response to low levels of RBCs.

Question 34

What does erythropoietin stimulate?

Answer 34

CFU-E

Question 35

What do nurse cells do?

Answer 35

Macrophages that phagocytose the nucleus after an RBC expels it.

Question 36

What will you see in peripheral blood if the need for RBCs is especially high?

Answer 36

A higher number of reticulocytes as the body keeps pumping out the baby RBCs to erase the deficit.

Question 37

What makes a reticulocyte a reticulocyte?

Answer 37

Fine reticulum of RNA and protein still in the cell from the maturation process.

Question 38

What is the progression from Myeloblasts to specific granules (n,e, or b)?

Answer 38

Myeloblasts -> Promyleocytes -> myelocytes -> specific granules

Question 39

What are stab/band cells and what do they indicate if elevated?

Answer 39

Immature neutrophils, in times of great neutrophil need they can be released from marrow more frequently

Question 40

What is weird about megakaryoblasts?

Answer 40

They undergo endomitosis (chromosome duplication but no division) and are thus polyploid.

Question 41

What does the CFU-Meg progenitor produce?

Answer 41

Megakaryoblast and Promegakaryocyte

Question 42

Are B cells immunocompetent by the time they leave the bone marrow?

Answer 42

Yes

Question 43

Are T cells immunocompetent by the time they leave the bone marrow?

Answer 43

No, they must mature in the thymus

Question 44

What are the 2 major classes of T cells?

Answer 44

CD4 and CD8

Question 45

What are the stages of monocyte maturation?

Answer 45

CFU-GM -> monoblast -> promonocyte -> monocyte

Question 46

Define anemia.

Answer 46

The reduction of the ability to carry oxygen to tissues, usually due to a reduction of the number of circulating RBCs.

Question 47

What are the 3 classes of anemia?

Answer 47

1. Too few RBCs 2. Too many RBCs (polycythemia) 3. Inadequate RBC function (e.g. sickle cell)

Question 48

Define leukemia.

Answer 48

Abnormal qualities or quantitites of white blood cells (leukocytes).

Question 49

What are the classifications of leukemia?

Answer 49

Acute or Chronic Myeloid or Lymphoid Thus ALL, AML, CLL, CML

Question 50

What do lymphoid leukemias refer to?

Answer 50

Cells deriving from CLP

Question 51

What do myeloid leukemias refer to?

Answer 51

Cells deriving from CMP

Question 52

At what age is red marrow no longer predominant?

Answer 52

4 years

Question 53

What is the stroma?

Answer 53

Supporting tissue (e.g. in bone marrow adipose, reticular cells, connective tissue, blood supply(

Question 54

What is the parenchyma?

Answer 54

The functional tissue

Question 55

What are the mesenchymal derived cells?

Answer 55

Osteoblasts Adipocytes Fibroblasts Endothelial cells

Question 56

What are the hematopoietically derived cells?

Answer 56

Osteoclasts | Macrophages

Question 57

PHSCS are ____potent

Answer 57

totipotent

Question 58

The first precursor cell in each lineage is a "_____"

Answer 58

blast. (e.g. myeloblast)

Question 59

Are cells weeded out at each step of stem/progenitor/precursor cells?

Answer 59

Yes! Die via apoptosis

Question 60

At what stage of maturation do granulocytes leave the marrow and enter the bloodstream?

Answer 60

Band cells or sometimes even fully mature

Question 61

What are the earliest granules to develop in granulocytes?

Answer 61

Azurophilic (primary)