stem cells Flashcards
what is meant by totipotency?
the cell is capable of differentiating into any type of cell
they express tumour rejection antigens
where are totipotent stem cells found?
in the zygote around 4 days post fertilisation
what is meant by pluripotency?
the ability of the cell to differentiate into any of the three germ layers
express tumour rejection antigens
what are the three germ layers?
endoderm
mesoderm
ectoderm
where are totipotent stem cells found?
within the inner cell mast within the blastocyst
what are the ethical issues surrounding the use of totipotent and pluripotent cells?
there is a risk of terminating a pregnancy when obtaining them
what is meant by multipotency?
the ability of the cell to differentiate into a limited number of cell types in their lineage
less chance of immune rejection and there are few ethical implications
where are multipotent stem cells found?
within their tissue lineages
what are stem cells?
cells with the unique ability to develop into a specialised cell through the process of differentiation
what is a stem cell niche?
the microenvironment around stem cells that provides support and signals that regulate self renewal and differentiation
what occurs in the absence of Wnt signalling ?
beta catenin is phosphorylated by the axin complex
what occurs in the presence of Wnt signalling?
axin is sequestered at the membrane
cytoplasmic beta-catenin translocates to the nucleus and binds to T-cell factor
this results in the transcription of proliferation related genes
