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PATHOLOGY > 4. Hematopoiesis > Flashcards

4. Hematopoiesis Flashcards

1
Q

What is hematopoiesis?

A

Production of new blood cells

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2
Q

What are agranulocytes?

A

Includes lymphocytes and monocytes
Occasionally contain granules but they will be low in numbers
when granules are present, often difficult to see

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3
Q

What are granulocytes?

A

Includes neutrophils, eosinophils and basophils
Characterized by granules and segmented nucleus

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4
Q

What is the lifespan of blood cells?

A

Neutros - 4-6hrs
Eosino - 30min
Baso - 4-6hrs
Monos - 2-3days
Lymphos - months to years
Erythrocytes - 2-5 months
Platelets - 4-6 days

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5
Q

When and where does hematopoiesis begins

A

Begins during early emryonic life
In the prenatal animal, occurs in the liver, spleen, thymus and red bone marrow
Red bone marrow is primary site for blood cell prod in the neonate and juvenile animals - found in the foetus and yng animal

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6
Q

in adult animals, where is hematopoiesis?

A

The red bone marrow is primary production site, but few bones contain red bone marrow.
Spleen and liver can help with hematopoiesis during periods of stress

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7
Q

Where is red bone marrow found in adult animals

A

Long bones, ribs, sternum and hips

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8
Q

What cell do all blood cells arise from?

A

Pluripotent stem cells, capable of regen, stay at constant, low numbers within the bone marrow

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9
Q

What do hematopoietic stem cells differentiate into?

A

Two progenitors
Common myeloid progenitor
Common lympoid progenitor
How they divide is determined by interactions with cytokines (~24)

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10
Q

What is erythropoiesis and how does it work?

A

Production of RBC’s
Erythropoietin (EPO) is primary cytokine for RBC production
Primarily prod in kidney (sm in liver)
Normally present in sm amounts in plasma to replace dying or aging RBC
EPO travels within blood to bone marrow, then binds to erythroid precursor cells to stimulate erythropoiesis. Stimmed by hypoxia

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11
Q

With erythropoiesis, where are dead cells removed?

A

Removed by the phagocytic cells in the spleen

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12
Q

At what age stage are RBC’s released? How long does it take dogs, cattle?

A

Only mature and possibly a few near-to mature cells are released from the bone marrow
Cattle takes 4 days, dogs is 7 days

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13
Q

What happens with hypoxia and erythropoiesis?

A

Bone marrow can inc its prod of RBC by 4-5 times normal
Provided that all the necessary materials are available
The time req for release of new red cells to peripheral blood following hypoxic stimulus is about 3-4 days

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14
Q

What happens in dogs with hypoxia and erythropoiesis

A

In dogs, the kidney is the sole source of erythropoietin
Dogs with several renal dz may have anemia as a complication
this is significant problem in cats with severe renal dz as the carotid body is involved with erythropoiesis

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15
Q

What is a rubiblast

A

A large cell (slightly bigger than neutrophil)
round cell and nucleus, thin rim of dark blue (basophilic) cytoplasm
Nucleoli present (paler in color, one or more present)
preinuclear clear zone is often preserved
A rubiblast can prod 8-16 mature cells

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16
Q

What is a prorubricyte?

A

Slightly smaller than the rubriblast
no nucleoli
nucleus more condense
often prominent pernuclear clear zone
basophilic cytoplasm

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17
Q

What is a rubricyte?

A

Significantly smaller than prorubricyte
nuclear chromatin shows an alternating light/dark pattern
Nucleus is dark purple
In early stages, cytoplasm is blue
Cytoplasm will gradually lighten and turn pink as hemoglobin (Hgb) matures

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18
Q

What is metarubricyte?

A

Nucleus appears as a dark blue circle
Cytoplasm is deep red and skewed off to one side prod a comet tail appearance
Slightly lger than a mature erythrocyte
No longer capable of cell division
Hemoglobin formation is complete

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19
Q

What is a reticulocyte?

A

Polychromasia
Anuclear
contains ribosomal material which gives the cell a blue/purple appearance when stained
macrocytic
Seen as polychromasia on Wright’s stain
seen as aggregated material with reticulocyte stain (Dark blue)

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20
Q

What does an erythrocyte look like?

A

Anuclear
no ribosomal remnants remaining
cytoplasm is pink due to mature Hgb

21
Q

What is a megakaryoblast?

A

Larger than other blast cells in the bone marrow
contains a single nucleus
very basophilic, scant ctyoplasm

22
Q

What is a promegakaryocyte

A

Containts 2-4 nuclei - nuclei continue to replicate
Nuclear lobes remain connected
cytoplasm doesn’t divide and consists of a rim around the nuclear mass

23
Q

What is a megakaryocyte

A

Extremely large (50-200uM) in diameter at maturity
Numerous nuclear lobes are present
Cytoplasm is abundant, pale blue and contains reddish cranules
The cytoplasm extends into thin, finger-like projections that become platelets as they get sheared off the cell

24
Q

What does a platelet lok like?

A

stage at which they leave the bone marrow
not true cells bc they have no nucleus. They are fragments of the megakaryocyte cytoplasm
lots of size and shape variations

25
Which species have different maturation phase?
Reptiles, amphibians, birds posses a nuclei and are true thrombocytes
26
How is granulopoiesis triggered?
Triggered by the hormone leukopoietin as well as several other cytokines
27
What are the two groups that granulocytes divide into?
Prliferation pool - cells capable of mitosis, includes myeloblasts, promyelocytes and myelocytes Maturation pool - cells can no longer divide, includes metamyelocytes and band cells
28
How are neutrophils produced?
Prod exclusively in the active bone marrow of healthy, adult animals Yng animals, some prod will occur in the spleen With chronic inflam dz, prod of the neutrophils will occur in spleen, liver and lymph nodes of adults
29
What is a myeloblast?
Involved in granulopoiesis lg cell, round to oval nucleus nucleus contains one or more nucleoli A few reddish granules may be present in cytoplasm Pale gray-blue cytoplasm - difficult to distinguish from other primitive blast cells larger and lighter in color than rubriblasts
30
What is promyelocyte
Slighter smaller and lighter than myeloblasts contains azurophilic granules (pink or purple) Occasionally nucleoli may be present - will be less prominent than in myeloblast More cytoplasm than the myeloblast
31
What are myelocyte
Slightly smaller and lighter in color than promyelocytes Nucleus is round and ccentrically placed no nucleoli granules are visible as neutrophilic, eosinophilic or basophilic
32
What is a metamyelocyte
similar to the myelocyte but nucleus is indented lighter colored cytoplasm can no longer undergo cell division
33
What is a band neutrophil
same color as the mature, segmented neutrophil nucleus is indented to the point of being U-shape, with parallel sides and clubbed ends
34
What is a segmented neutrophil
purple/lavender colored nucleus nucleus is segmented granules may or may not be distinct Hypersegmented neutrophil - lobes inc with age so >5 is hypersegmented
35
How to know if its band cell or segmented neutrophil
narrowest region of nucleus needs to be less than or equal to 2/3 of the width widest part of the nucleus to be classed as a segmented neutrophil
36
If you see the start of a hematopoiesis sequence, will you see all cell stages, or just the start?
You wil not see a stage skiped on a smear. If you see myeloblasts, you will see all the stages in btw If you see band neutrophils, then you will see those + segs but won't see the predecessors
37
How should we categorize cells? What about if you count disintegrating cells?
Always categorize cells by the most mature stage if unsure only count disintegrating cells if >10% of the WBC's counted
38
What is the transit time of neutrophils?
the amount of time needed for the myeloblast to mature into a segmented neutrophil In healthy animals, transit time is 7 days When stimulated due to inflam, can be as little as 2 days
39
What is circulation time in neutrophils
The amount of time btw the release of the cell into the blood and its arrive in tissue in good health, ~6-10hrs The neutrophil pool is renewed 2-3 times per day Samples drawn within a few hours can be very different
40
What should we keep in mind with monocytic series?
isn't responsive to an infection in the way the neutrophilic series is Only rarely overcome by a neoplastic disorders wont be seen unless you do bone marrow work
41
For monopoiesis, what is the order of maturity and where are they located
Monoblast - Loc in bone marrow, similar to myeloblasts but had irregularly shaped nucleus Promonocyte - loc in bone marrow, similar to myelocytes and metamyelocytes Monocyte - mature monocyte move into peripheral blood, maye develop if exposed to specific cytokines Macrophage - loc in tissues
42
What are lymphopoiesis triggered by and what do they differentiate into?
tiggerd by cytokines and antibodies starts with the common lymphoid precursor stem cell - found in bone marrow differentiate into T-lymp, NK precursor or B-lympho precurso
43
What does a lymphoblast look like?
high nuclear to cytoplasmic ratio (N:C ratio) - the cell is comprised mostly of nucleus, very little cytoplasm present oval to indented, eccentrically placed nucleus, dark clue cytoplasm
44
What is a prolymphocyte
decreased N:C ratio - cytoplasm makes up a greater volume of the cell large nucleoli lighter staining cytoplasm
45
What does a lympocyte look like?
round to slightly indented nuclei dense, relatively smooth chromatic, small amount of basophilic cytoplasm
46
Where do juvenile B-lymphocytes mature?
in the bone marrow or ileal peyer's patche in dogs, pigs and ruminants bursa of fabricius in birds
47
Where do t0lymphocytes mature
Thymus
48
Where do NK cells mature in the bone marrow
Can develip in thymus and other lymphoid tissue
49
Where might immature stages be seen with lymphopoiesis
may be seen in peripheral blood due to neoplastic dz - relatively common in cats usually would only note that immature stages are present (this along with c/s & hz are diagnostic) usually due to a virally-induced neoplastic disorder cells usually seen @ feathered edge will be abnormal in size &/or color may see nucleoli may contain mitotic figured (cells that are seen to be dividing)

PATHOLOGY (19 decks)

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