BLOODBLOOD
By
Hanaa S. E. Mousa
Lecturer of Histology
HEMOPOIESIS
Definition
The formation of blood elements(RBCs,
white blood cells, and platelets) from
immature precursor stem cells
Site in healthy adults:
Bone marrow
Phases:
Before birth ( Mesoplastic Phase in
mesoderm)
Hepatic Splenic Myeloid
After birth:
Bone barrow normally
Extramedullary in liver and spleen
when needed
Types of Bone Marrow
Red bone marrow:
Predominant in intrauterine life and
children
Present in flat bone in adults (scapula,
vertebrae, ribs, skull, sternum)
Yellow bone marrow:
Present in shaft of long bone ( can revert to
red bone marrow in hemorrhage)
Red Bone marrow
Red Bone marrow
Blood cells in the bone
marrow
Hematopoietic stem cells
Progenitor cells
Precursor cells
Hematopoietic stem cells
Pluripotential stem cells
Give all types of cells
Progenitor cells
Multipotent
Precursor cells
Unipotent, can’t self renew
First cell to be recognized
Blood is composed of
Plasma
Formed elements:
Platelets
Blood cells:
RBCs
WBCs
Granulocytes:Neutrophils , Eosinophils, Basophils
Agranulocytes:Lymphocytes , Monocytes
BloodBlood
PLATELETS
Small, disc-shaped non-nucleated cell
fragments
From megakaryocytes
2-4 micrometer in blood smears
250,000-400,000 / cubic mm
LM of platelets
It has no nucleaus
Cytoplasm :
Hyalomere: pale blue peripheral
zone
Granulomere:dark central region
contain purple granules
EM of platelets
Hyalomere:Hyalomere:
electron-lucent
Thick cell membrane with glycocalyx
(covering)
10-15 parallel microtubules and
microfilaments forming a ring just
below the cell membrane
GranulomereGranulomere::
Granules+ Few Ribosomes , Some
Mitochondria , and Glycogen Particles
Three types of granules
Alpha (α )
Delta (δ )
Lambda( λ )