REVIEW OF STEM CELLS
Dr. B.Naresh
GS ‐ IV PG
WHAT HAPPENS AFTER MEIOSIS?
• WHAT DID MEIOSIS PRODUCE?
GAMETES
2N
2N
1N
1N
1N
1N
1N
4 HAPLOID SPERM
1N
1N
1N
1N
1N
4 HAPLOID EGGS
1N
1N
WHAT HAPPENS AFTER MEIOSIS?
• WHAT DID MEIOSIS PRODUCE?
• WHAT HAPPENS TO GAMETES?
FERTILIZATION
Image courtesy of L. De Vos‐ U.L.B.‐ Biodic
http://www.ulb.ac.be/sciences/biodic/biodic/images/bio_animale/embryologie/fecondation/baefec_01_01.jpg
WHAT HAPPENS AFTER MEIOSIS?
• WHAT DID MEIOSIS PRODUCE?
• WHAT HAPPENS TO GAMETES?
• WHAT’S THE PRODUCT OF FERTILIZATION?
ZYGOTE
The fertilized egg
http://en.wikipedia.org/wiki/Image:Sperm‐egg.jpg#file
WHAT HAPPENS AFTER MEIOSIS?
• WHAT DID MEIOSIS PRODUCE?
• WHAT HAPPENS TO GAMETES?
• WHAT IS THE PRODUCT OF FERTILIZATION?
• HOW DOES A ONE CELL ZYGOTE BECOME A HUMAN?
EMBRYOGENESIS
http://stemcells.nih.gov/info/scireport/appendixA.asp
Image courtesy of NIH resource for stem cell research
http://embryo.soad.umich.edu/carnStages/carnStages.html
Image courtesy of Brad Smith, University of Michigan
SO…..WHAT ARE STEM CELLS?
• are bilogical cells found in multicellular
organisms, that can divide and differentiate into diverse specialized cell types and can self renew to produce more stem cells.
Stem cells
http://stemcells.nih.gov/info/basics/
"Image courtesy of NIH resource for stem cell research"
STEM CELLS ‐‐
properties
• Self Renewal
• Differentiation potential
SELF RENEWAL
• Obligatory asymmetric replication
• Stochastic differentiation
DIFFERENTIATION POTENTIAL
• TOTIPOTENT ( Morula )
• PLURIPOTENT
• MULTIPOTENT
• OLIGOPOTENT ( Lymphoid, Myeloid )
• UNIPOTENT ( Muscle Stem Cells )
WHERE DO STEM CELLS COME FROM?
• EMBRYONIC
– BLASTOCYST
• “ADULT”
–
–
–
–
CORD CELLS
PLACENTA
CHILDREN
ADULTS
EMBRYONIC STEM CELLS
Blastocyst
http://en.wikipedia.org/wiki/Image:Blastocyst_English.svg
http://stemcells.nih.gov/info/basics/
"Image courtesy of NIH resource for stem cell research"
http://stemcells.nih.gov/info/basics/
"Image courtesy of NIH resource for stem cell research"
EMBRYONIC STEM CELLS ARE
OBTAINED FROM
INVITRO‐ FERTILIZATION EMBRYOS THAT WERE NOT USED
http://www.news.wisc.edu/packages/stemcells/illustration.html
“ADULT” STEM CELLS ARE OBTAINED IN A VARIETY OF WAYS
Illustration by Matt Bohan, 2007
STEM CELLS HAVE ALSO BEEN FOUND IN “MATURE” ORGANS
Illustration by Matt Bohan, 2007
PROS AND CONS OF EACH TYPE
• EMBRYONIC
• ADULT – CELL LINES LAST AND LAST AND LAST
– CELL LINES DO NOT LAST
– MULTIPOTENT
– NOT MULTIPOTENT
– EASY TO FIND
– HARD TO LOCATE
– ETHICAL ISSUES ‐
WHEN DOES LIFE BEGIN?
– NO ETHICAL ISSUES Thank you