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.
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.
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
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
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
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
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
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
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.
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