MTAP W4 (Rodaks: Megakaryopoiesis/Platelets Flashcards by JHOANNA LYNN LUMBOY

Q

nonnucleated blood cells
diameter of 2.5 mm
150 to 400 x 10^9/L
higher in women
lower in both sexes when over 65 years old

A

Platelets

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Q

trigger primary hemostasis

A

Platelets

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Q

Wright-stained wedge-preparation blood film
7 to 21 cells per 1003 field

A

platelets

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Q

30 to 50 mm in diameter- multilobulated nucleus and abundant granular cytoplasm
0.5% of all bone marrow cells
are the largest cells in the bone
marrow and are polyploid, possessing multiple chromosome
copies
2-4 per LPF

A

Megakaryocytes

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Q

product of the X chromosome gene

A

GATA

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Q

product of the ZFPM1 (zinc finger protein multitype 1)
gene

A

FOG1

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Q

In order of differentiation
least mature

A

burst-forming unit (BFU-Meg)

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Q

In order of differentiation
the intermediate

A

colonyforming unit (CFU-Meg)

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Q

In order of differentiation
the more mature progenitor

A

light-density CFU (LD-CFU-Meg)

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Q

All three progenitor stages of megakaryocytes resemble - and cannot be distinguished by Wright-stained light microscopy

A

lymphocytes

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Q

progenitor stage/s

participate in normal mitosis, maintaining a viable pool of megakaryocyte progenitors

A

BFU-Meg and CFU-Meg

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Q

progenitor stage

loses its capacity to divide but retains its DNA replication and cytoplasmic
maturation: ENDOMITOSIS

A

LD-CFU-Meg

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Q

is a form of mitosis that lacks telophase and cytokinesis (separation into daughter cells)

A

Endomitosis

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Q

Endomitosis

transcription slows

A

GATA-1
FOG1

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Q

Endomitosis

transcription factor; mediates the switch from mitosis to endomitosis by
suppressing the Rho/ROCK signaling pathway, which suppresses the assembly of the actin cytoskeleton

A

RUNX1

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Q

Endomitosis

transcription factor; DNA replication proceeds to the production of 8N, 16N, or even 32N ploidy with
duplicated chromosome sets

A

NF-E2

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Q

Some megakaryocyte nuclei
replicate five times, reaching -; this level of ploidy is unusual, however, and may signal hematologic disease

A

128N

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Q

A single megakaryocyte may shed - platelets

A

2000 to 4000

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Q

A single megakaryocyte may shed 2000 to 4000 platelets, a process called -

A

thrombopoiesis or thrombocytopoiesis

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Q

megakaryocytes: a total turnover rate of -days.

A

8 to 9 days

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Q

platelet production rises by as much as tenfold

A

thrombocytopenic purpura

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Q

As endomitosis proceeds, megakaryocyte progenitors leave the
proliferative phase and enter -

A

terminal differentiation

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Q

a series of stages in which microscopists become able to recognize their unique Wright-stained morphology in bone marrow aspirate
films

A

terminal differentiation

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Q

Morphologists call the least differentiated megakaryocyte
precursor the -

A

MK-I stage or megakaryoblast

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Q

Megakaryocyte Differentiation Stages

Nucleus: round

A

MK-I

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Q

Megakaryocyte Differentiation Stages

Nucleus: Indented

A

MK-II

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Q

Megakaryocyte Differentiation Stages

Nucleus: Multilobed

A

MK-III

Q

Megakaryocyte Differentiation Stages

Chromatin: homogenous

A

MK-I

Q

Megakaryocyte Differentiation Stages

Chromatin: moderately condensed

A

MK-II

Q

Megakaryocyte Differentiation Stages

Chromatin: deeply and variably condensed

A

MK-III

Q

Megakaryocyte Differentiation Stages

N/C ratio: 3:1

A

MK-I

Q

Megakaryocyte Differentiation Stages

N/C ratio: 1:2

A

MK-II

Q

Megakaryocyte Differentiation Stages

N/C ratio: 1:4

A

MK-III

Q

Megakaryocyte Differentiation Stages

Cytoplasm: basophilic

A

MK-I

Q

Megakaryocyte Differentiation Stages

Cytoplasm: basophilic and granular

A

MK-II

Q

Megakaryocyte Differentiation Stages

Cytoplasm: azurophilic and granular

A

MK-III

Q

Megakaryocyte Differentiation Stages

Endomitosis: present

A

MK-I

Q

Megakaryocyte Differentiation Stages

Endomitosis: ends

A

MK-II

Q

Megakaryocyte Differentiation Stages

Endomitosis: absent

A

MK-III

Q

biologically identical to the megakaryocyte plasma membrane
and ultimately delineates the individual platelets during thrombocytopoiesi

A

DMS/demarcation system

Q

Nuclear lobularity first becomes apparent as an indentation at the 4N replication stage, rendering the cell identifiable as an -

A

MK-II stage, promegakaryocyte

Q

The promegakaryocyte reaches its full ploidy level by the end of the - stage

A

MK-II

Q

the most abundant - stage, the
megakaryocyte is easily recognized at 103 magnification on
the basis of its 30- to 50-mm diameter

A

MK-III

Q

ploidy levels are measured using

A

mepacrine

Q

a nucleic acid dye in megakaryocyte flow cytometry

A

mepacrine

Q

flow cytometric megakaryocyte membrane
marker

which is the TPO receptor site present
at all maturation stages

A

MPL

Q

flow cytometric megakaryocyte membrane
marker

disappears as differentiation proceeds

A

CD34 marker

Q

The platelet membrane
glycoprotein -
first appears on megakaryocyte progenitors and remains
present throughout maturation, along with immunologic
markers CD36, CD42, CD61, and CD62

A

glycoprotein IIb/IIIa

Q

a marker located on the IIb portion

A

CD41

Q

shows platelet shedding

A

Thrombocytopoiesis

Q

growth hormone
70,000 Dalton molecule
possesses 23% homology with the red blood cell–producing
hormone erythropoietin

A

TPO

Q

primary source of mRNA for TPO

A

liver

Q

The plasma concentration of TPO is - proportional to platelet and megakaryocyte mass

A

inversely

Q

also induces the proliferation and maturation
of megakaryocytes and induces thrombocytopoiesis, or platelet
release

A

TPO

Q

a nonimmunogenic oligopeptide
that is also effective in raising the platelet count in immune
thrombocytopenic purpura

A

romiplostim

Q

Other cytokines that function with TPO to stimulate megakaryocytopoiesis include interleukin -

A

3,6,11

Q

interleukin: seems to act in synergy with TPO to induce the early differentiation of stem cells

A

IL-3

Q

interleukin: act in the
presence of TPO to enhance the later phenomena of endomitosis, megakaryocyte maturation, and thrombocytopoiesis

A

IL-6 and IL-11

Q

stimulates platelet production in patients with chemotherapy-induced thrombocytopenia

A

IL-11

Q

transcription factors -
diminish megakaryocytopoiesis at the progenitor, endomitosis,
and terminal maturation phases

A

FOG1, GATA-1, and NF-E2

Q

MARKERS:

MPL, TPO receptor by FCM

A

BFU-Meg
CFU-Meg
LD-CFU-Meg
MK-I
MK-II
MK-III
PLTs

Q

MARKERS:

CD41: b3 portion of aIIbb3; peroxidase by TEM cytochemical stain

A

BFU-Meg
CFU-Meg
LD-CFU-Meg
MK-I
MK-II

Q

MARKERS:

CD42; GP Ib portion of VWF
receptor, by FCM
PF4 by FCM
VWF by immunostaining

A

BFU-Meg
CFU-Meg
LD-CFU-Meg
MK-I

Q

MARKERS:

CD34; stem cell marker by FCM

A

BFU-Meg
CFU-Meg
LD-CFU-Meg

Q

MARKERS:

Fibrinogen

A

PLTs