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