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Mechanisms of
Teratogenesis:
Developmental defects may be traced to one of 4 processes
that occur during organogenesis:
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Cell proliferation
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Cell migration
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Cell death
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Cell differentiation
Cell proliferation:
If a generalised inhibition of the process of cell proliferation
occurs, this is incompatible with embryonal survival .
Cell migration:
Can lead to heterotopia if it doesn’t occur.
Example - canine thyroid tissue can be left behind in thorax and distal
neck as well as in the correct position next to the larynx.
Cell death:
Must occur to eliminate foetal structures such as pronephros
and metanephros in kidney development Involves tissue remodelling. Inhibition
of cell death leads to persistence of embryonal tissues. For example,
in development of the digits, there must be necrosis of interdigital
tissue. If this does not occur then there is failure of digit separation,
resulting in syndactyly.
Cell differentiation:
Must occur for tissues to develop different functions.
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