Lesson 2: MEGAKARYOPOIESIS

Question 1

Overview of the cycle of Megakaryopoiesis

Answer 1

Megakaryoblast > Promegakaryocyte > Megakaryocyte >Platelets

Question 2

It proceeds initially through a phase
characterized by mitotic division of a progenitor cell,
followed by a wave of nuclear endoreduplication.

Answer 2

Megakaryocytopoiesis

Question 3

is the process in which chromosomal material (DNA) and the other events of mitosis occur without subsequent division of the cytoplasmic membrane into identical daughter cells.

Answer 3

Endoreduplication

Question 4

It is the hormone thought to stimulate the
production and maturation of megakaryocytes, which in
turn produce platelets, has recently been purified and
cloned.

Answer 4

Thrombopoietin

Question 5

These substances have been shown to be able to increase
megakaryocyte size, maturational stage, and ploidy. What are these substances?

Answer 5

erythropoietin, IL-3, and granulocyte-
macrophage colony-stimulating factor (GM-CSF).

Question 6

Thrombopoietin activity results from several different
cytokines such as:

Answer 6

erythropoietin, IL-3, and granulocyte-
macrophage colony-stimulating factor (GM-CSF)

Question 7

What is the size of the Megakaryoblast?

Answer 7

10-24 mm

Question 8

What is the shape of the nucleus of the Megakaryoblast?

Answer 8

Round

Question 9

How many nucleoli does a Megakaryoblast have?

Answer 9

2-6

Question 10

What does a Megakaryoblast’s chromatin look?

Answer 10

Homogeneous, loosely organized

Question 11

Megakaryoblast’s cytoplasm is…

Answer 11

Basophilic

Question 12

A Megaryoblast’s granules is absent or present by Wright’s stain?

Answer 12

Absent

Question 13

What is the nucleus to cytoplasmic ratio of a megakaryoblast?

Answer 13

3:1

Question 14

What is the size of the Promegakaryocyte?

Answer 14

15-40 mm

Question 15

What is the shape of the nucleus of the promegakaryocyte?

Answer 15

Indented

Question 16

How many nucleoli does a Promegakaryocyte have?

Answer 16

Variable

Question 17

What does a Promegakarycyte’s chromatin look?

Answer 17

Condensed

Question 18

Promegakaryocyte’s cytoplasm is…

Answer 18

Basophilic

Question 19

A Promegaryoblast’s granules is absent or present?

Answer 19

Present

Question 20

What is the nucleus to cytoplasmic ratio of a promegakaryocyte?

Answer 20

1:2

Question 21

They are the largest bone marrow cells, ranging up to 160 mm in size

Answer 21

Megakaryocyte

Question 22

The megakaryocyte has a nuclear-cytoplasmic ratio as high as…

Answer 22

1:12

Question 23

What does a megakaryocyte’s nucleoli look like?

Answer 23

Nucleoli are no longer visible

Question 24

What is a distinctive feature of the megakaryocyte?

Answer 24

It is multilobular, not multinucleated

Question 25

What happens to the fully mature lobe of a megakaryocyte on the completion of maturation?

Answer 25

The fully mature lobes of the
megakaryocyte shed platelets from
the cytoplasm on completion of
maturation.

Question 26

What is the average diameter that a platelet has?

Answer 26

2 to 4 mm

Question 27

Are younger platelets larger than old ones?

Answer 27

Yes

Question 28

Do megakaryocytes have a nucleus?

Answer 28

Yes

Question 29

Do platelets have a nucleus?

Answer 29

No

Question 30

What is the color of a platelet’s cytoplasm and its granules?

Answer 30

Light blue with EVENLY dispersed, fine RED-PURPLE granules

Question 31

It circulates as a thin, smooth-surfaced disc.

Answer 31

inactive or unstimulated platelet

Question 32

Platelets circulate WHERE? THROUGH WHAT? WITHOUT WHAT?

Answer 32

Platelets circulate at the center of the flowing bloodstream through endothelium-lined blood vessels without interacting with other platelets or with the vessel wall.

Question 33

Stronger stimulation causes platelets to become what?

Answer 33

Sticky without losing their discoid shape

Question 34

alteration in cellular shape is triggered by WHAT?

Answer 34

an increase in the level of
cytoplasmic calcium.