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Gelatinous vascular CT richly endowed with hematopoietic cells

Describe the morphology of bone marrow.

Destroy extruded nuclei of RBC precursors, malformed cells, and excess cytoplasm.

What is the role of macrophages in the bone marrow?

Hemopoiesis

____ is the formation of blood cells in the body.

yolk sac

In the early fetus, hemopoiesis occurs in the ____.

liver and spleen

In the late fetus, hemopoiesis occurs in the ____.

WBCs and platelets
RBC

At 5 months, the fetal bone marrow begins to produce ____, but ____ production doesn't begin until about 7 months.

bone marrow of almost all bones of body

Where does hemopoiesis occur in early childhood?

bone marrow of vertebrae, ribs, skull, pelvis, and proximal femurs

WHere does hemopoiesis occur in adulthood?

Extramedullary hemopoiesis

____ is the development of hemopoietic activity in the liver and spleen in response to diseased bone marrow

Newborn bone marrow is actively engaged in RBC production, hence, it is called red marrow. At about 20 years old, there is an accumulation of fat and absence of hemopoiesis in the shafts of long bones, hence it is called yellow marrow

Describe the changes that occur in the bone marrow with age.

Pluripotential stem cells

____ can form any of the blood cells.

bone marrow and sites of blood cell formation, very few can be found in peripheral blood

Where are pluripotential stem cells found?

lymphocytes

What do pluripotential stem cells resemble?

they display distinctive cell-surface antigens

How are pluripotential stem cells identified?

Multipotential stem cells

____ are capable of forming a specific, but wide range of cells.

Committed progenitor cells

____ are unipotential, which means they are capable of forming only one cell line and they have limited self-renewal capacity.

Committed precursor cells

____ have specific morphological characteristics that permit them to be identified as first cell of particular cell line. They are incapable of self-renewal.

Colony forming unit-GEMM (CFU-GEMM)
Colony forming unit-lymphocyte (CFU-Ly)

List the two principal multipotential stem cells that are derived from the pluripotential stem cell.

colony forming units (CFUs)

Under proper conditions, ____ can occasionally give rise to groups of cells composed of granulocytes, RBCs, monocytes, lymphocytes, and platelets.

PHSC > CFU-GEMM >BFU-E > CFU-E > proerythroblast > basophilic E > polychromatophilic E > orthochromatophilic E > reticulocyte > erythrocyte

Stage of development of an erythrocyte.

PHSC > CFU-GEMM > CFU-MEG> megakaryoblast > megakaryocyte

Stage of development of megakaryocyte.

PHSC > CFU-GEMM> CFU-Eosinophil > myeloblast > promyelocyte > Eo. myelocyte > Eo. metamyelocyte > Eo. stab > eosinophil

Stage of development of eosinophil.

PHSC > CFU-GEMM > CFU-Basophil > myeloblast > promyelocyte > Ba. myelocyte >Ba. metamyelocyte > Ba. stab > basophil

Stage of development of basophil.

PHSC > CFU-GEMM > CFU-GM > CFU-G > myeloblast > promyelocyte > N myelocyte > N metamyelocyte > N stab > neutrophil

Stage of development of neutrophil.

PHSC > CFU-GEMM > CFU-GM > CFU-M (monoblast) > promonocyte > monocyte

Stage of development of monocyte.

PHSC > CFU-Ly > CFU-Ly T > T lymphocyte > T lymphoblast > T lymphocyte

Stage of development of T lymphocyte.

PHSC > CFU-Ly > CFU-Ly B > B lymphocyte > B lymphoblast > B lymphocyte

Stage of development of B lymphocyte.

Induce rapid mitosis (proliferation), differentiation, or both. Some also promote function of mature blood cells.

What are the general effects of growth factors?

colony stimulating factors (CSFs)

____ cause proliferation and maturation/activation of precursors/progenitor cells of the granulocytic and monocytic series.

increases the number and proliferative activity of CFU-E

What is the function of erythropoietin?

Stimulate growth and proliferation following excessive loss due to chemotherapy.
Stimulate increased blood cell population in light of chronic anemia

How might growth factors be used in the clinic setting, especially in cases of chemotherapy and chronic anemia?

Bone marrow sinusoids, reticular support cells, extracellular matrix containing collagen, laminin, and fibronectin facilitate adhesion of hematopoietic cells to marrow stroma. In addition, proteoglycans such as chondroitin sulfate, hyaluronic acid, and heparan sulfate may bind to growth factors to control hemopoiesis.

How does bone marrow create an environment for hemopoiesis?

Steel factor

____ is produced by stromal cells of the bone marrow and inserted into their cell membranes.

Controls mitotic activation of pluri-, multi-, and uni-potential stem cells. Each of these must come into contact with Steel factor before they can become mitotically active.

What role does Steel factor play?

Erythropoiesis

____ is the formation of RBCs.

proerythroblast

Precursor of erythrocyte: ____ 25 μm, divides to form 8-16 cells; large acidophilic nucleus, rim of basophilic cytoplasm.

basophilic erythroblast

Precursor of erythrocyte: ____ smaller cell, basophilic cytoplasm, perinuclear halo

polychromatic erythroblast

Precursor of erythrocyte: ____ smoothed cytoplasm, enlarging amount of cytoplasm.

orthochromatic erythroblast

Precursor of erythrocyte: ____ pinkish hue to cytoplasm, visible nucleolus

reticulocyte

Precursor of erythrocyte: ____ extrusion of nucleus, pink cytoplasm.

decreasing cell size
hemoglobin production
decrease & eventual loss of all organelles
change of stain from intense basophilia (from polyribosomes) to eosinophilia
condensation and eventual extrusion of nucleus

What are 5 cellular changes that occur during erythropoiesis?

Orthochromatic erythroblast

At which stage does the developing erythroblast lose the ability to divide?

They basically determine how actively RBCs are produced. More importantly, they point to causes of anemia, whether it is from decreased RBC production or increased RBC destruction.

Describe how reticulocyte counts are used in clinical practice.

body is actively trying to combat anemia by producing more RBCs

What is the significance of an elevated reticulocyte count?

Granulopoiesis

____ is the formation of granulated WBCs.

myeloblast

The ____ is the precursor cell for all of the granulocytes.

myeloblast

Precursor of granulocyte: ____ has a large cell with huge nucleus, obvious nucleoli, scanty cytoplasm with few granules

promyelocyte

Precursor of granulocyte: ____ more abundant cytoplasm, more primary granules, nucleoli are still present

myelocyte

Precursor of granulocyte: ____ flattening/invagination of one face of nucleus, cytoplasm contains mixture of granules; nucleoli disappear.

metamyelocyte

Precursor of granulocyte: ____ significant invagination of nucleus to a reform shape.

stab/band cell

Precursor of granulocyte: ____ horseshoe shaped nucleus.

Basophils

____ are readily distinguishable at the early myelocyte stage by their huge abundance of granules.

Nucleoli disappear, nuclei shrink and become lobulated/cleft, cytoplasm grows and fills up with granules

What are the changes that occur during differentiation and maturation of granulocytes?

Early myelocyte stage

What is the stage at which developing granulocytes can be distinguished from one another?

metamyelocyte

At what stage in granulocyte development is mitosis no longer possible?

stab/band cells

____ are late stage metamyelocytes.

It belongs to the granulocytic cell lines.

To which cell lines does the band/stab cell belong?

bacterial infection

What is the clinical significance of finding neutrophilic band cells in a peripheral blood smear?

thymus
bone marrow

T cells develop in the ____ whereas B cells develop in the ____.

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