Meghan Barboza, PhD
Online Course
Red Bone Marrow
 Bone marrow: site of
blood cells formation
(hemopoiesis or
hematopoeisis)
 Divided into two
compartments:
 Vascular
 Hemopoietic
Bone Marrow
 Vascular compartment:
 Arteries, veins and
sinusoids

Sinusoids (originate
from nutrient arteries
and empty into central
veins) conduits for new
blood cells and
platelets from
megakaryocytes
Hemopoiesis
 Hemopoietic
compartment: A mix of
blood cells at different
stages of development
Erythroblast
Erythroblas
Wikipedia commons
Hemopoiesis
 Hemopoietic
compartment: very
loose c.t. w/ stem cells,
developing blood cells,
fibroblasts, collagen
fibers and scattered
adipose
 Red to yellow pulp
depending on amount
of adipose
Erythrocyte Production
(Erythropoesis)
Hemopoietic
stem cell
Colony-forming
unit (CFU)
Erythrocyte CFU
Precursor
cells
Erythroblast
Copyright © McGraw-Hill Education.
Mature
cell
Reticulocyte
Erythrocyte
Squiggly arrow = A band neutrophil; arrow with tail = Segmented neutrophil;
arrowhead = plasma cell; thin arrow = nucleated red cell (erythroblast).
Bone trabeculae (big arrow) and immature myeloid cells (thin arrow) and an
erythroid precursor (arrowhead). A neutrophil is present away from the bone
trabeculae (arrow with tail).
Thrombocyte
 Platelets formed by
megakaryocyte – giant
cell housed in bone
marrow:
 undergoes continual
fragmentation process
Thrombopoeisis
 Mature vs.
immature
Megakaryocyte
Pseudopod
Granules
Platelets or
Thrombocytes
• Thrombopoiesis
– Stem cells triggered by
thrombopoietin
– Megakaryoblasts
– Megakaryocytes
Open
canalicular
system
Mitochondria
(a)
2 µm
Platelets
Bloodflow
Endothelium
Proplatelets
Sinusoid of
bone marrow
RBC
WBC
Megakaryocyte
(b)
a: ©NIBSC/Science Photo Library/Science Source
http://www.free-ed.net/freeed/Resources/PubServ/EMS/EMS%20Pri
mer/emsPrimer01.asp?iNum=704
Check Your Understanding
• If someone had a disease that affected the
myelocytes, which adult cells would be affected?
• Leukemia is a cancer of the bone marrow that
results in immature white blood cells called blasts
in the blood. One type of treatment is a bone
marrow transplant, what cells are needed for this
to be successful?
• Why do you think there is fat in bone marrow?