Pathology 4200A/B Lecture 2: Stem Cells & Cancer
4 Oct 2017
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Yeast culture: yeast divide by budding give rise to mother + daughter cell (cell developed from bud, em shows scar area that(cid:495)s ~1% of the sa of cells. Bud is never formed here: life-span of individual cells is limited by depletion of available budding sites, cells typically bud 20-25x & enter a short post-replicative state followed by lysis. Fibroblast culture: three phases, slow growth/establishment of culture, rapid proliferation, proliferation stops, possible causes of the transition to phase 3 hayflick. Hayflick: the finite lifetime of diploid cell strains in vitro may be an expression of aging or senescence at the cellular level. No proliferation despite continued viability & metabolic activity. Limit: 40-60 divisions: aging occurs in mammalian cells not yeast cells, 35+ trillion cells total, cells involved in development, cells involved in maintenance/homeostasis. Dualists: myeloid & lymphoid cells derived from distinct cells. Asymmetric (maintenance & differentiation: majority of stem cells, homeostasis.
