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The Science and Ethics of
Stem Cell Research
Stem Cell
Development
Lesson 1
An Overview of Early Development
modeled with Play-Dough
Fertilized egg
Totipotent: Can become any cell in
body or placenta
Pluripotent: Can become any cell in
body
Totipotent
stem cells
Fate Decision
Pluripotent
stem cells
(3-5 days old)
Blastocyst
Multipotent: Can become any cell
within a specific germ layer or cell
lineage
Embryonic stem cells come from inner cell mass of blastocyst.
Fate Decision
Implantation
Multipotent
Gastrulation (day 14) leads to
Primary Germ Cells
Endoderm (inner)gdigestive tract, resp. track
Mesoderm (middle)gbones, blood cells, heart
Ectoderm (outer)gskin, CNS
What your zygote might look like:
The Zygote
What your morula might look like:
Early Cell Division
Source: Florida Institute for Reproductive Science and Technologies
Four-cell stage
2 days after fertilization
Source: Florida Institute for Reproductive Science and Technologies
Eight-cell stage
3 days after fertilization
Courtesy: RWJMS IVF Program
Source: Florida Institute for Reproductive Science and Technologies
Morula
4 days after fertilization
Source: Florida Institute for Reproductive Science and Technologies
16 cells
What your blastula (blastocyst)
might look like:
Blastula
5 days after fertilization
Source: Florida Institute for Reproductive Science and Technologies
Courtesy: RWJMS IVF Program
Five Day Embryo
http://www.nationalgeographic.com/ngm/
Blastula (Blastocyst)
This image has been released into the public domain.
What your gastrula might look like:
Sea Urchin Development
One Cell to Blastula Stage
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http://www.luc.edu/depts/biology/dev/urchindv.htm
(courtesy of Dr. J. Hardin, Univ. of Wisconsin)
http://www.exploratorium.edu/imaging_station/gallery.php?Asset=celldiv&Category=seaurchins&Type=video
Early Mouse
Development
One Cell to
Morula Stage
Early Human Development
Multipotent
This graphic has been released into the public domain