Early Embryogenesis
Embryogenesis:
— formation of body structures & organs (organogenesis)
— requires cell division (proliferation) and cell differentiation (specialization)
— produces the great variety of cell types and extracellular products found in the body.
Cell specialization:
— selective gene expression (and resultant protein production) is the ultimate explanation for
the cell differentiation process during embryogenesis.
— genetic expression by a particular cell depends on the cell’s previous genetic history (commitment lineage) and its current cellular environment (intercellular communications).
Cell differentiation is the result of cells expressing some genes and suppressing others
within a common genome. Cells differ because they produced different proteins/peptides.
Proteins & peptides are:
— structural components (cytoskeleton or extracellular structures)
— enzymes (controlling cell metabolism)
— secretory products (e.g., hormones; digestive enzymes; etc.)
— channels & pumps (passage of molecules across membranes)
— receptors (communication, etc.)
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