This document discusses hematopoiesis, the formation of blood cells. It presents two main theories: the monoplastic theory which states all blood cells originate from one stem cell, and the polyplastic theory which suggests different blood cell types originate from different stem cells. The stages of blood cell development are described starting from the embryonic stage through the hepatic and medullary stages where development occurs in the bone marrow. The processes of erythropoiesis and granulopoiesis, leading to the production and maturation of red blood cells and white blood cells, are outlined in detail through their characteristic cell types.

1. HEMATOPOIESIS
JOSE R. VILLARINO, RMT

2. Theories on Blood Cell Formation
 A. MONOPHYLETIC THEORY
All blood cells come from one origin stem
cell the HEMOCYTOBLAST REC
 B. POLYPHYLETIC THEORY
Also known as Dualistic Theory which
suggests different groups of blood cells
originate from different stem cells.
- RBC,WBC, platelets – Hemohistioblast
- Monocytes, lymphocytes & plasma cells –
Tissue hemohistioblast

3. Stages of Hematopoiesis
 Mesoblastic stage – first month of
embryonic life where cells are formed
outside the embryo in the mesenchyme of
the yolk sac.
 Hepatic stage – by the 6th week
 Medullary stage – by the 5th month blood
cell formation occurs in the bone marrow.
- Marrow – primitive stem cells &
committed progenitor cells are confined
- Spleen & lymph nodes – 2ndary lymphoid
tissue for lymphocyte development and
differentiation.

4. Principles in Normal Cell Maturation
 CELL SIZE – immature cells are much
bigger than more mature cells
 CYTOPLASMIC DIFFERENTIATION
- amount of cytoplasm
- color (basophilia)
- presence of granules (WBC)
 NUCLEAR MATURATION
- presence, size (nucleus:cytoplasm ratio)
- nucleolus presence & lobes or indentation

5. ERYTHROPOIESIS
 Governed by a hormone produced by
the kidneys called ERYTHROPOIETIN
 Begins with the multipotential stem
CFU-S. By the action of
microenvironmental factors the CFU-
S differentiates forming a committed
erythroid progenitor cell.

6. RBC Maturation Program
 Pronormoblast (Erythroblast)
 Basophilic normoblast (Prorubricyte)
 Polychromatic erythroblast
(Rubricyte)
 Orthochromic normoblast
(Metarubricyte)
 Reticulocyte (Polychromatophilic)
 Mature erythrocyte

7. Pronormoblast (Rubriblast)
 First recognizable RBC precursor
 First Hemoglobin-synthesizing cell
 Approximately 20 um
 Moderate amount of cytoplasm
 Basophilic cytoplasm with 1-3 nuclei
 Prominent nuclear membrane
 Shows active mitotic division

8. Pronormoblast (rubriblast)

9. Basophilic normoblast
(prorubricyte)
 Slightly smaller than the rubriblast
 Cytoplasm is moderate in amount
with deep basophilia due to high
amounts of cytoplamsic RNA
 Nucleoli are present though not
always visible
 Active mitotic division noted

10. Prorubricyte (Basophilic normoblast)

11. Polychromatic erythroblast
(rubricyte)
 Cytoplasm stains various shades of
gray due to mixture of RNA and
hemoglobin
 Nuclear volume occupies half of the
cell area
 May undergo 1 or mitotic division in
which after the last division the
nucleus become small & condensed

12. Rubricyte (polychomatic erythroblast)

13. Orthochromic normoblast
(metarubricyte)
 Last nucleated stage in RBC series
 First non-mitotic stage
 Slight polychromasia
 Abundant or full hemoglobinization

14. Metarubricyte (orthochromic normoblast)

15. Reticulocyte
 Non-nucleated immature RBC
 Appears polychromatic due to remaining
RNA responsible for the bluish-gray color
on air-dried smears
 Larger than mature erythrocyte
 Released into the circulation after 2 days of
maturation in the marrow
 Synthesize Hemoglobin for approximately 1
day after leaving the bone marrow

16. Reticulocyte
(poychromatophilic erythrocyte)

17. Reticulocyte (supravital stain)

18. Mature Erythrocyte
 Appears as a biconcave disc with a
concavity on each side – “Discocyte”
 Average size 7.2 um

19. Erythrocyte (mature RBC)

20. Granulopoiesis (WBC)
 Hematopoietic growth factors
influencing formation of WBCs
Strict lineage:
 G-CSF (colony stimulating factor) –
granulocytes (neutrophils)
 M-CSF – monocytes
Multilineage:
 GM-CSF – granulocytes, monocytes,
megakaryocytes & RBC

21. Cells of the WBC series
 Myeloblast
 Promyelocyte
 Myelocyte
 Metamyelocyte
 Band or stab
 Segmenter

22. Myeloblast
 Earliest cell in the WBC series
 Nucleus:cytoplasm ratio of 4:1
 Large, round nucleus with 2-5 visible
nucleoli
 Deeply basophilic cytoplasm
 No granules noted

23. Myeloblast

24. Promyelocyte
 Slightly smaller than myeloblast
 Basophilic cytoplasm
 N:C ratio of 2:1 with visible nucleoli
 Presence of azurophilic granules

25. Promyelocyte

26. Myelocyte
 Appearance of the specific granules or
also known as secondary granules
 Specific granules will determine the
functional destiny of the WBC giving
rise to eosinophil, basophil or
neutrophil.
 N:C ratio 1:1 with almost invisible
nucleoli. Cytoplasm show mixture of
basophilic and acidophilic staining

27. Myelocyte

28. Metamyelocyte
 Also known as the JUVENILE
 Differentiated from the myelocyte
because of the presence of
indentation of its nucleus
 N:C ratio 1:1 and smaller than the
myelocyte

29. Metamyelocyte (juvenile)

30. Band or Stab
 Also known as the STAFF
 Measures 12-13 um
 Nucleus is sausage-shaped, elongated
or horse-shoe shaped in appearance
there is no lobulation or segmentation
noted.

31. Band / Stab / Staff

32. Segmenter
 Most mature stage of the WBC
 N:C ratio of 1:2
 Nucleus shows lobulation or segments
 Differentiated based on the
appearance of its granules as follows:
- Eosinophil – reddish-orange granules
- Basophil – blue-black granules
- Neutrophil – pink-tan granules

33. Neutrophilic segmenter

34. Eosinophil

35. Basophil