WBC morphology

Describe the wedge method of making a blood smear.

1. Place a drop of whole blood on a slide

2. Take a second slide and draw it back

3. Take second slide and push forward to form a feathered edge

What are characteristics of a good blood smear?

does not cover the full slide surface, thick to thin blood transition, feathered edge, air dried with low humidity

What two dyes are used to stain a blood smear?

Methylene blue/azure B and eosin

What structures does the methylene blue stain?

basophilic structures like nuclei and platelets

What structures does the eosin stain?

hemoglobin

What can cause RBCs to take on a pale blue coloring?

• methylene blue stain left on too long

• methylene blue stain not washed off enough

• basic or alkaline reagent

• blood film too thick

What can cause RBCs to take on a bright red-orange coloring?

• eosin stain left on for insufficient times

• eosin stain washed off too much

• acidic reagent

What is the formula for absolute count?

% of cell type in smear * total WBC count

What is the nucleus?

holds chromatin and nucleoli

What is chromatin?

material inside of the nucleus, polymers of DNA

What is the nucleolus?

space inside nucleus where ribosomes are produced

What is the cytoplasm?

Protoplasm that holds organelles

What is active chromatin?

lightly stained, unwound chromatin that is actively replicating

What is inactive chromatin?

dark stained, tightly wound chromatin not being replicated

What are the four chromatin patterns?

Fine, lacy, coarse, clumping

What percent of a blood smear should make up neutrophils?

54-62%

Describe the nucleus and cytoplasm appearance of a neutrophil.

Nucleus: dark, irregular band or segment shape, coarse chromatin

Cytoplasm: lighter pink with granules

If we observe a “shift to the right”, what does that observation mean?

the neutrophils are hypersegmented

What percent of a blood smear should make up band neutrophils?

0-6%

Describe the nucleus and cytoplasm of a band neutrophil.

Nucleus: dark, but not as dark as a seg, U shape

Cytoplasm: pink with four granules

If we observe a “shift to the left”, what does that observation mean?

increased neutrophil bands

What percent of a blood smear should make up eosinophils?

0-4%

Describe the nucleus and cytoplasm of an eosinophil.

Nucleus: not as dark as a neutrophil, segmented or immature band

Cytoplasm: colorless with pink granules all over

What percent of a blood smear should make up basophils?

0-2%

Describe the nucleus and cytoplasm of a basophil.

Nucleus: hard to see but dark, less lobulated

Cytoplasm: filled with deep purple granules containing histamine and heparin

What percent of a blood smear should make up monocytes?

3-7%

Describe the nucleus and cytoplasm of a monocyte.

Nucleus: less dark, finer chromatin, one single entity either indented or horseshoe shaped

Cytoplasm: blue-gray with frosted glass appearance and vacuoles

What percent of a blood smear should make up lymphocytes?

25-35%

Describe the nucleus and cytoplasm of a lymphocyte.

Nucleus: sharply defined round, no lobes, blocks of chromatin

Cytoplasm: pale blue

If we have a blood smear that is too long, how should the angle be changed?

increased