Module 2: Erythropoeisis, Granulopoeisis, Leukopoeisis, Monopoeisis

Erythropoeisis

Erythropoeisis

Erthyropoeitin (EPO)

• glycoprotein hormone that mediates feedback mechanism

• 38/34kD

• Secreted by Kidneys

• Binds to specific receptors on CFU-E & BFU-E

Target cells of EPO

CFU-E and Pronormoblasts

90% undergo extravascular lysis

• macrophage mediated

• senescent rbc are disposed by splenic macrophages

10% undergo intravascular lysis

happens in the blood circulation

Peritubular fibroblast

Hypoxia

Stimulus for erythropoeisis

Pronormoblast

• Rubriblast/Proerythroblast

• earliest recognizable stage

• 14-20 um

• 1-2 nucleoli

• cytoplasm

  • lighter-staining, basophilic

• N:C 8:1

• Mitosis

  • 2 Basophilic normoblast

• HGB

  • production preparation

Basophilic Normoblast

• Prorubricyte/Basophilic erythroblast

• Nuclear chromatin is slightly coarser

• cytoplasm

  • darker-staining, basophilic

• N:C 6:1

• 10-15um

• 0-1 nucleolus

• 2 mitoses

  • 8 polychromatic normoblast

Polychromatic normoblast

• Rubricyte/Polychromatophilic erythroblast

• 10-15um

• cytoplasm

  • blue-gray to pink gray

• N:C 4:1

• RNA (Basophilic)

• HGB

  • production begins (acidophilic cytoplasm)

• Last stage of Mitosis

  • 16 Orthochromic normoblast

Orthochromic normoblast

• Metarubricyte

• 7-12um

• Pyknotic nucleus (condensed) w/o nucleoli

• N:C 1:2

• Cytoplasm

  • pink due to predominance of HGB

• Last stage w/ nucleus

Reticulocyte

• 7-10um

• 2 or more reticular dots (RNA)

• supravital stains

  • new methylene blue

  • brilliant cresyl blue

• No nucleus

Erthrocyte

• Mature RBC

• 6-8um

• round

• pink-peach and salmon pink

• anucleated

• 1/3 central pallor

• biconcave

Granulopoeisis stages

1. Myeloblast

2. Promyelocyte

3. Myelocyte

4. Metamyeolocyte

5. Stab/Band/Staff

6. Granulocytes

Myeoloblast

• 15-20um

• earliest recognizable stage in the lineage

• Cytoplasm

  • blue

• Nucleus

  • round or slightly oval

  • red-purple

  • 2-5

• N:C 4:1

Promyeolocyte

• 15-21um

• Cytoplasm:

  • pale pink to bluish (primary granules)

• Nucleus

  • oval or round

• N:C 3-1 to 2:1

• Chromatin:

  • Coarser

• Little bit bigger than pyeloblast

Myelocyte

• 12-18um

• Cytoplasm:

  • moderate

  • secondary granules

  • specific granules

• 3 differentiated granulocytes

• Nucleus:

  • oval/round

  • eccentric

  • N:C 1:1

  • no nucleoli

• Chromatin:

  • coarse

  • more condensed

Neutrophil myelocyte

• pinkish specific granules

• seen near the nucleus

Eosinophil myelocyte

• red-orange specific granules

• bigger than non-specific & specific granules of neutrophil

Basophil myelocyte

• few and large

• dark blue-purple specific granules

Metamyelocyte

• 10-15um

• Nucleus:

  • indented

  • kidney-shaped

  • decreased N:C

• Full complement of specific granules

  • few non-specific granules

Neutrophilic metamyelocyte

• granules:

  • more pink

  • more numerous

Eosinophil metamyelocyte

• granules:

  • brighter orange-red

  • more numerous

Basophil metamyelocyte

• granules:

  • dark purple to black

  • more numerous

Stab/Band/Staff cell

• 9-15um

• cytoplasm:

  • same as metamyelocyte

• Nucleus:

  • elongated/band-shaped

  • more deeply-indented

• Chromatin:

  • more coarse & clumped

Segmented Neutrophil

• 9-15um

• granules:

  • rose-violet specific

  • few non-specific

• Nucleus:

  • not covered by its granules

Eosinophil

• 9-15um

• granules:

  • full complement of large reddish-orange

• Nucleus:

  • bi-lobed wc

• Chromatin:

  • coarse & clumped

Basophil

• 10-16um

• Cytoplasm:

  • slightly pink to colorless

• Granules:

  • dark purple-black specific

  • water soluble

• Nucleus:

  • not coarse

  • unsegmented

  • rarely bi-lobed

  • covered by its granules