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Fate of Cells

Fate of Cells

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Fate of Cells

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  1. Fate of Cells • The developing embryo undergoes morphogenesis in order to create different tissues and organs through cleavage, gastrulation, and organogenesis • Morphogenesis… changing of form, shape, or function • Cleavage… pinching off to form 2 structures or a division within a structure • Gastrulation… forming a cavity • Organogenesis… specialization of tissue for a function

  2. Cell Differentiation • Cells are totipotent in the first 16 cells of the of the blastocyst • Potency is reduced with each cell specialization there after • Initial differentiation due largely to uneven distribution of cytoplasmic determinants in the yolk of the egg • Egg is polarized creating heterogeneous cytoplasm • Cleavage creates uneven distribution of mRNA and asymmetrical cell division • Process of induction causes the specialization of most cells • Created through contact via diffusible chemical signals

  3. Fate Mapping • Manipulation of embryonic cells to determine the lineage of cells from the first cleavage event

  4. Cellular Asymmetries • Axes of body plan • Anterior-posterior, ventral-dorsal, right-left • Establishes bilateral symmetry • 1st step in morphogenesis and tissue/organ formation • Bicoid region of flies • Determined by melanin in the yolk during oogenesis • Gravity helps determine anterior/posterior axis in chicks • pH determines ventral/dorsal…marked by the gray crescent in many embryos