Erythrocytes Flashcards
What is an erythron?
All erythroid cells in an animals
What is erythropoiesis a part of?
Hematopoiesis
What is erythropoietin produced by?
Fetal liver and adult kidney
Renal peritubular interstitial cells in response to hypoxia
What is hypoxia?
Anemia
Poor oxygenation of the blood
Decreased renal perfusion
What signals erythrocytes to stop dividing?
Increasing Hgb concentrations
What is produced for protein synthesis including Hgb?
RNA
What leads to nucleus extrusion in mammals?
Maturation of erythrocytes
What is a reticulocyte?
An erythrocyte without the nucleus but with high concentration of RNA
What happens to old erythrocytes?
Loose metabolic ability to keep deformability
Expose hidden antigens in the membrane that naturally occurring antibodies bind to mediating erythrocyte destruction
What is hemoglobin?
Tetramer of four globin molecules and bound to a internal Heme molecule
Why can heme alone not transport O2?
It has a Ferrous ion associated and that cannot transport O2
What percent of CO2 from tissues binds to Hgb? What happens with the rest of CO2?
20%
It reacts with H2O to form H+ hand HCO3-
What happens in order to excrete CO2 from the lungs?
The reaction is reversed
What is porphyria?
Increased concentration of porphyrins in erythrocytes, plasma, or urine
Can be acquired or congenital
What percent of iron is in erythrocytes?
50-70%
What percent of iron is in storage?
25-40%
What is absorption of iron regulated by?
Hepcidin
What is hepcidin produced by?
Hepatocytes
What decreases hepcidin production? What then happens to iron absorption?
Hypoxia
Fe absorption decreases
What increases hepcidin production?
Inflammation
What stains RNA and mitochondria?
New methylene blue causing a reticulated or punctuated structure look in erythrocytes cytoplasm
What are the types of reticulocytes?
Most species are all RNA rich erythrocytes will be called reticulocytes
Cats have punctuate with 2-6 granules and aggregate with large aggregates
What is reticulocytosis?
Semiquantitative evidence of erythropoiesis
Cats: aggregate started at 2 days, peaks at 4 days; punctate is mild in day 1, peaked at 7-14 days
What is the level of reticulocytes like in cattle and dogs when looking for erythropoiesis?
Starts 3-4 days and peak 7-14 days
What is the level of reticulocytes like in cats when looking for erythropoiesis?
Aggregate started at 2 days, peaks at 4 days
Punctate is mild in day 1, peaked at 7-14 days
What is the level of reticulocytes like in horses when looking for erythropoiesis?
They rarely will have circulating reticulocytes
What is polychromasia?
Increased numbers of basophilic erythrocytes in the blood smear
What does increased reticulocytes mean?
That bone marrow is responding to EPO
What is an erythogram?
Morphologic evaluation Hematocrit or PCV Hgb concentration Erythrocytes count Wintrobe's erythrocytes indices Nucleated erythrocytes
What is a part of the Wintrobe’s erythrocytes indices?
MCHC
MCV
MCH
What is MCHC?
Average of 100 mL of erythrocytes [Hgb]
What is MCV?
Average of erythrocytic volume
What is MCH?
Average [Hgb] per average sized erythrocytes
How are nucleated erythrocytes counted?
Per 100 leukocytes and if they are present, it is necessary to correct the leukocytes count
How are nRBCs usually reported?
#/100 WBC So, if nRBC= 50/100 WBC that could be a lot or very few If WBC= 500 μL, nRBC would be 250/μL If WBC= 50,000 μL, nRBC would be 25,000/μL
What is the reticulocyte concentration?
#/μL or L RC= RP x [RBC]
What is the reticulocyte percentage or reticulocyte count?
# of reticulocytes per 100 erythrocytes Percentage of erythrocytes that are reticulocytes in the blood
What is the corrected reticulocyte percentage?
Calculated number if RP if animal was not anemic but had the same RC
CRP= RP x (patient’s Htc/avg Hct for species)
What are dicocytes?
Mature normal erythrocytes
What is rouleaux caused by?
Charges interactions
What does agglutination occur in?
Immune hemolytic anemia
How is agglutination different from rouleaux?
Will not form stacks of cells
Cannot use a saline dispersion test
What is rubricytosis?
Increased number of nRBCs in the blood
When is rubricytosis appropriate?
Response to EPO stimulus
With reticulocytosis
When is rubricytosis inappropriate?
Loss of control of nRBC release from BM BM damage Extramedulary hematopoiesis Splenic contraction Splenectomy Lead poisoning in dogs BM dyscrasia in poodles with macrocytosis
What is central pallor?
Central area of an erythrocytes that is more clear because it is thinner
Increased is hypochromasia
Decreased is abnormal shape
What is a ghost cell?
Complement mediated intravascular hemolysis
Artifact
What is a hypochromic erythrocyte?
Hyperchromasia: increased number of hypochromic erythrocytes
Decreased MCHC and CHCM
Decreased RBC [Hgb]
Fe deficiency
What is a polychromatophil?
An erythrocyte with enough RNA to stain basophilic with Wright stain
What reflects accelerrated erythropoiesis?
Polychromasia and reticulocytosis
What is the preferred method for evaluating marrow response to anemia?
Reticulocyte concentration
Describe anaplasma marginale in erythrocytes
0.5 μm small coccus in the internal margin of the erythrocyte Usually one, but possibly multiple per cell Causes hemolysis (immune mediated)
Describe anaplasma centrale in erythrocytes
0.5 μm small coccus within the erythrocyte
Usually one, but possibly multiple per cell
Causes hemolysis (immune mediated)
Describe Babesia in erythrocytes
Intracellular, oval to teardrop trophozoites
Variable sizes
Pale blue with a darker outer membrane and a purple eccentric nucleus
Hemolus: immune mediated, protease activity, decreased cell pliability, oxidative damage
Describe Cytauxzoon felix in erythrocytes
Intacellular, oval, 0.1 to 2 μm with outer thin rim and eccentric nucleus
One to several per cell
Anemia: inflammation, BM damage, hemolysis
Describe distemper (dogs) in erythrocytes
Round to variably shaped, pale blue to pink, homogeneous inclusions
0.3 to 3 μm
Diff-quick is better to see than Wright stain
Active distemper infection
Describe Mycoplasma (cattle) in erythrocytes
Rind, rod, or cocci on erythrocytes’ surface
0.3 to 3 μm
Immune hemolysis
Describe Mycoplasma hemocanis in erythrocytes
Thin chain of cocci
Immune hemolysis
Describe Mycoplasma hemofelis in erythrocytes
Thin chain of cocci, small rings, pale blue to purple
Less than 0.1 μm
Immune hemolysis
Describe Candidatus Mycoplasma haemominutum in erythrocytes
Coccie 0.1 to 0.2 μm, individual or short chains
Immune hemolysis
Describe Theileria in erythrocytes
Pleomorphic piroplasm: cocci. rings, rods, pears, and maltese crosses
Anemia: immune, protease, decreased cell pliability, and oxidative damage
What are causes of basophilic stippling?
Regenerative anemia
Plumbism
What is the pathogenesis of regenerative anemia?
Persistence of ribosomal RNA
What is the pathogenesis of plumbism?
Inhibition of pyrimidine 5’-nucleotidase
How does a Heinz body develop?
Exposure to oxidants
Pathogenesis: oxidized Hgv precipitates
How does a Howell-Jolly body develop?
Increased erythropoiesis, decreased splenic function
Pathogenesis: nuclear remnant free in the cytoplasm
How do siderotic granules develop?
Excess Fe in the body, plumbism in dogs, myeloproliferative diseae
Pathogenesis: Fe accumulates in damaged mitochondria or in autophagocytic vacuoles
How does an acanthocyte develop?
Hemangiosarcoma; splenic, hepatic, and renal disorders
Pathogenesis: not known how it is formed in domestic mammals, possible changes in membrane lipids or erythrocyte fragmentation
How does a codocyte (mexican hat cell) develop?
Regenerative anemias; hepatic, renal, and lipid disorders
Pathogenesis: excess membrane relative to Hgb content, possibly membrane lipid changes
How does a dacrocyte develop?
Marrow diseases such as myelofibrosis and neoplasia (pathogenesis: unknown formation mechanism)
Artifact (pathogenesis: stretching during film preparation
How does an eccentrocyte form?
Exposure to oxidants, G6PD or FAD deficiencies
Pathogenesis: fusion of damaged membranes
What are the different types of echinocytes?
Irregularly shaped cells (type I)
Regularly spaced blunt projections (type II)
Regularly spaced pointed projections (type III)
What is the pathogenesis of echinocytes?
Erythrocyte dehydration, strenuous exercise, doxorubicin toxicosis, antonic in dogs, PK deficiency in dogs, rattlesnake and coral snake envenomation
What are crenated erythrocytes?
Always an artifact
Features of types I, II, and III echinocytes
All echinocytes should be considered artifact until proven otherwide
How does a keratocyte develop?
Vasculitis, intravascular coagulation, hemangiosarcoma, caval syndrome, endocarditis
Pathogenesis: trauma, oxidative injury, vesiculation have been proposed
How does an ovalocyte develop?
Protein band 4.1 deficiency in dogs, myelofibrosis, idiopathic in cats, iron deficiency
Pathogenesis: abnormal membrane proteins in hereditary forms, otherwise unknown
How do pyknocytes develop?
Exposure to oxidants
Pathogenesis: likely formed from eccentrocytes
How does a schistocyte develop?
Intravascular coagulation, vasculitis, hemagiosarcoma, caval syndrome, endocarditis
Pathogenesis: trauma
How do spherocytes develop?
Immune hemolysis, fragmentation hemolysis, envenomation, clostridial infections
Pathogenesis: membrane loss due to macrophages partial phagocytosis, trauma
How does a stomatocyte develop?
Young erythrocytes, herediatry stomatocytosis in dogs
Pathogenesis: folding of excess membrane
What is the pathogenesis of torocytes?
Artifact
Do not confuse these with hypochromia
What is anemia?
Decreased Hct, [Hgb], [RBC]
Pathological state, not a disease
What are causes of anemia?
Loss
Destruction
Lack of production
What is a regenerative anemia?
With reticulocytosis (increased number of reticulocytes)
Following blood loss or erythrocyte destruction (hemolysis); erythroid neoplasia in cats; resolution of nonregenerative anemia
Show active erythropoiesis
May be blunted by other concurrent conditions
What is a nonregenerative anemia?
Without reticulocytosis (normal or decreased numbers of reticulocytes)
Defective or reduced erythrocyte production
Persistent status shows that BM is not able to produce cells
When does reticulocytosis occur?
3-4 days after EPO stimulus and will peak at 7-10 days
What is normocytic?
Based on MCV
Maturation is not defective
What is macrocytic?
Based on MCV
Presence of reticulocytes or defective cells
What is microcytic?
Based on MCV Extra mitosis (Fe deficiency); fragments
What is normochromic?
Based on MCHC/CHCM
Hgb synthesis is complete
What is hypochromic?
Based on MCHC/CHCM
Hgb synthesis is incomplete (young cells or defective synthesis)