ms. he's stem cells
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Embryogenesis Summary
Germ cells
Zygote Morula Blastula Blastocyst Gastrula
Fertilization BlastulationCleavage Gastrulation
Hatching & Implantation
Embryogenesis
http://www.mymcat.com/wiki/Embryogenesis
blastocyst
-Tight junction-Outcome of mitosis-2n
Ferlization Mitosis
- Solid mass of cells
Blastulation
-Hollow mass of cells
Embryogenesis: Fertilization
• Germ cells / sex cells:– sperm, ovum– Haploid (1 copy of each chromosome,
half the genetic information)• Zygote: fertilized egg– Diploid (2 copies of each chromosome)
http://www.mymcat.com/wiki/Embryogenesis
Blastocyst
• Differentiation begins in the blastocyst
• Inner cell mass: becomes the embryo and some extraembryonic tissue
• (Outer) Trophoplast: becomes the placenta
http://www.kumc.edu/images/stemcell/looklike.jpg
Embryogenesis: Gastrulation
• Gastrula is composed of 3 germ layers:– Outer: Ectoderm–Middle: Mesoderm– Inner: Endoderm
http://www.mymcat.com/wiki/Embryogenesis
Embryogenesis: Gastrulation
3 germ layers will eventually differentiate into• Ectoderm: epidermis, nervous system• Mesoderm: muscle, bone, blood, urinary tract• Endoderm: GI tract, lungs
Video: The first 9 weeks of pregnancy
http://www.babycenter.ca/video/pregnancy/weeks-1-to-9-pregnancy/
http://i-newnews.com/wp-content/uploads/2012/01/3060_3083_31.jpg
Embryogenesis Summarized
Germ cells
Zygote Morula Blastula Blastocyst Gastrula
Embryonic Stem Cell (ESC)
PluripotentTotipotent
Fertilization BlastulationCleavage Gastrulation
Hatching & Implantation
Stem Cells
• Unspecialized / undifferentiated cell
• Has the potential of becoming a specialized cell with a specific function
• Property of self-renew for long periods of time (immortal)
• Formed during the development of the embryo
Stem cell division. A – stem cellsB – progenitor cellC – differentiated cell
Types of Stem Cells
• Embryonic stem cells– Stem cells taken from the pre-
implantation stage of the embryo– Totipotent or pluripotent
• Somatic / Tissue / Adult stem cells– Exist within specialized tissue– Able to differentiate into certain types of
cells –Multipotent
Proliferative Potential: Potency
• A cell’s potential to differentiate
• Levels of potency:– Totipotent– Pluripotent–Multipotent– Unipotent– Terminally
differentiated
Totipotent
• Capable of giving rise to any and all cell types– Somatic cells– Germ cells– Placenta
• Can form a whole organism / embryo• Totipotent cells: zygote, morula
Pluripotent
• Capable of giving rise to many cell types– Somatic cells– Germ cells
• Can not develop into an organism because incapable of producing extraembryonic tissue – placenta
• Pluripotent cells: blastocyst (inner cell mass)
Multipotent
• Also known as progenitor cells • Can give rise to multiple, but limited
number of lineages• Committed to produce specific cell
types and thus specialization potential is limited to one or more cell lines
• Adult / tissue stem cells: found in the tissues of adult mammals
Terminally Differentiated
• Cells that are unable to divide
• Example: neurons, adipocyte, cardiomyocyte, skeletal muscle cells, skin cells
Stem cell division. A – stem cells; B – progenitor cell; C – differentiated cell; 1 – symmetric stem cell division; 2 – asymmetric stem cell division; 3 – progenitor division; 4 – terminal differentiation
http://en.wikipedia.org/wiki/File:Stem_cell_division_and_differentiation.svghttp://www.ncbi.nlm.nih.gov/books/NBK6180/