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Haematopoiesis Flashcards

(46 cards)

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1
Q

Lymphoid stem cells becomes

A

B, T, NK cells

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2
Q

Myeloid stem cells become

A

Megakaryocytes -> platelets

Erythrocytes

All leukocytes except lymphoid cells

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3
Q

Where does differentiation of lymphoid stem cells, towards B cells, occur

A

WIthin the bone marrow

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4
Q

Where to primative T cells migrate to?

A

From the bone marrow to the thymus and other peripheral lymphoid tissue

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5
Q

Where does haematopoesis occur in neonates and immature animals?

A

All bones

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6
Q

Where does haematopoesis occur in adult animals?

A

Flat bones - pelvis, vertebrae, ribs
Proximal ends of long bones

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7
Q

What are the preferred sites for bone marrow aspiration in dogs and cats

A

Iliac crest
Proximal humerus
Femur

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8
Q

What are the preferred sites for bone marrow aspiration in large animals

A

Sternum (horses) and sometimes the ribs

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9
Q

Extramedullary haematopoeisis

A

Occurs when the bone marrow cannot produce new blood cells at a fast enough rate

Typical sites include the spleen, liver, and occasionally lymph nodes

Can be identified on cytology by presence of megakaryocytes (platelet precursors) and other precursor cells.

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10
Q

Erythropoiesis

A

Takes place in the bone marrow, in islets around a central nurse cells

Stimulated by erythropoietin (EPO) - produced by peritubular cells in the kidney (of adults) and the foetal liver - CKD can lead to anaemia

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11
Q

What diseases can lead to reduced EPO production, and so anaemia

A

CKD
Hypothyroidism
Hypoadrenocorticism
Etc.

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12
Q

Erythrocyte production

A

Erythroid stem cells -> pro-erythroblasts -> early normoblasts (rubricytes) -> intermediate and then late normoblasts (metarubricytes) -> extrusion of the nucleus produces a reticulocyte (mature in bone marrow for 1-2d) -> released into blood stream and reach full maturation after 24-48hrs

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13
Q

What does haemoglobin synthesis require?

A

Iron, vitamin B12, folate, amino acids

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14
Q

Life spans of mature erythrocytes

A

Cat 80d
Dog 110d
Horse 150d

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15
Q

What are polychromatophils?

A

Reticulocytes that are stained blue with Diff quick due to the clumps of ribosomes they contain. They are also larger than mature erythrocytes.

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16
Q

What are the two types of reticulocytes that can be seen in cats?

A

Aggregate reticulocytes: released from the bone marrow, appear as polychromatophils on blood smear, indicate regeneration, circulate for 12hrs then become punctate

Punctate reticulocytes: circulate for up to 4 weeks, not polychromatic, require methylene blue stain to see them

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17
Q

RBC

A

Red blood cell count

Number of erythrocytes (determined by analyser)

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18
Q

Hb

A

Haemoglobin concentration

Concentration of blood after red cells are lysed in vitro

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19
Q

HCT

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A

Haematocrit

Calculated from RBC and MCV values, can be erroneous if either are incorrect

Should correlate with PCV

20
Q

MCV

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A

Mean cell volume

Measure of erythrocyte size

21
Q

MCH

Study These Flashcards
A

Mean cell haemoglobin

Not a useful parameter

22
Q

MCHC

Study These Flashcards
A

Mean cell haemoglobin concentration

Measure of haemoglobin content of red cells

23
Q

RDW

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A

Red cell distribution width

Measure of variability in red cell size (anisocytosis), increased in regeneration

24
Q

PCV

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A

Packed cell volume

Gold standard measure of red cell mass

Determined by centrifugation

SHould correlate with HCT

25
PCV/HCT and/or Hb decreased
Suggests anaemia
26
PCV/HCT, RBC, and/or Hb are increased
Suggests erythrocytosis
27
Anaemia
A pathological state, rather than disease in itself Many possible causes
28
Clinical signs of anaemia
Lethargy Weakness Exercise intolerance Tachypnoea Tachycardia Pale mucous membranes Systolic heart murmur Bounding femoral pulses
29
Mild anaemia
Dogs: 30-37% Cats: 20-26%
30
Moderate anaemia
Dogs: 20-29% Cats: 15-19%
31
Marked/severe anaemia
Dogs: < 20% Cats: < 15%
32
Classification of anaemia causes
Loss of red cells (haemorrhage) Destruction of red cells (haemolysis) Reduced production of red cells (by bone marrow)
33
Regnerative anaemias
Caused by haemorrhage or haemolysis - loss of RBCs or reduced lifespan Leads to increased production of erythrocytes by the bone marrow Causes polychromasia/reticulocytosis
34
Non-regenerative anaemias
Caused by reduction of erythrocytes by the bone marrow No compensatory increase in red cell production
35
Features of regenerative anaemia
Evident 3-5d following haemorrhage or haemolysis Reticulocytosis - manual on methylene blue stained smears - automated Polychromasia - >7-10 per hpf of polychromatophils on blood smear Magnitude of response should correlate to degree/severity of anaemia Other supportive characteristics - anisocytosis - macrocytosis - rubricytosis - Howell-Jolly bodies - Target cells/codocytes - Basophilic stippling
36
Why do you not usually see reticulocytosis or polychromasia in horses with regenerative anaemia?
Because they retain reticulocytes in the bone marrow until they are mature erythrocytes before releasing them into the circulation.
37
Anisocytosis
Variation in red cell size and can be associated with regenerative responses, as well as other causes of macrocytosis (such as dyserythropoiesis, erythroleukaemia, FeLV infection) or causes of microcytosis (iron deficiency, portosystemic shunt, severe liver dysfunction)
38
Macrocytosis
The presence of larger erythrocytes. This can be associated with regeneration, dyserythropoiesis, erythroleukaemia, and FeLV infection.
39
Rubricytosis
The presence of nucleated red blood cells in the circulation. Low numbers can be seen in normal animals
40
Causes of rubricytosis without a regnerative response
Lead poisoning Bone marrow damage/sepsis Erythroleukaemia Splenic contraction or splenectomy
41
Howell-Jolly bodies
Nuclear remnants seen within mature erythrocytes Low numbers in normal cats Increase in regenerative anaemias and animals that have had a splenectomy (as RBCs usually phagocytosed in the spleen)
42
Target cells/codocytes
Cells that have low haemoglobin content and so have increased ratio of membrane:Hb Narrow rim of haemoglobin at the periphery with wide area of central pallor, and often central circle of haemoglobin Seen in regernative anaemias, iron deficiency, or with liver dysfunction
43
Basophilic stipling
Caused by the presence of ribsomes Seen in regenerative anaemias (usually in ruminants) If other signs of regeneration not seen then could be lead poisoning
44
Findings of haematology that could indicate a regerative anaemia
Reticulocytosis Serial increase in PCV over time (provided PP doesn't also increase as this could indicate dehydration) Increase in MCV and decrease in MCHC
45
Causes of mean cell volume (MCV) increase - macrocytosis
Regenerative anaemias In vitro cell swelling (especially during transport to the laboratory) FeLV infection Agglutination (artefact) Hypernatraemia Vitamin B12/folate deficiency Erythroleukaemia/myelodysplastic syndromes Inherited macrocytosis in poodles
46
Features of non-regenerative anaemias
No reticulocytosis (or lack of appropriate reticulocytosis for degree of anaemia) No or minimal polychromasia (<7 polychromatophils/hpf) Normocytic and normochromic (normal MCV and MCHC) No serial rise in PCV Persistent for more than 5 days

HOLS (11 decks)

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