HMB321H1 Lecture Notes - Lecture 18: Adult Stem Cell, Planarian, Symmetry In Biology
8 Oct 2011
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Hmb321 l18: bret pearson, planarians a new model to disease and regeneration. Prebilateria (not bilaterally symmetric, e. g. sponge and jelly sh) As well as lophotrochozoa (diverse species, e. g. annelids, snails, molluscs) Large uncondensed nucleus is a key characteristic (how it was found) Non-stem cells are differentiated and have condensed, small nuclei. C. elegans have 0 divisions and live only 4 days, whereas mice have more divisions and live up to 3 years, whereas humans have more divisions than mice and live 80 years or so, but . Stem cell is only as good as the lineage that it outputs. Maintenance of correct lineage is unknown process, especially in vertebrates. This maintenance goes awry in our 20s-30s => organismal senescence vs. cancer (in developed countries, in about 1 in 3 humans; hyper-proliferative) Hierarchal => start with non-stem cell (somatic cell) provides info for adult stem cell (asc) Stem cells are de ned by unique biology of self-renewal (multipotency)
