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COMMON
ORIGIN OF PANCREAS AND LIVER
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Recent studies have concluded that hepatic cells
and pancreatic cells differentiate from a set
of bipotential progenitor cells (9).
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MANIFESTATIONS
OF COMMON ORIGIN
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1) The progenitors of the pancreatic and hepatic cells arise at the
same time during embryogenesis (9). In a study
performed on mouse embryos, Pdx1 gene expression, which is specific to
pancreatic progenitors, was found to occur at the same time as serum albumin
and other liver-specific genes were activated in the ventral endoderm.
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Picture Credit: (1)
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2) The pancreas and liver arise from the same region geographically,
as is illustrated by the figure to the right, which presents a view of
the liver and pancreatic primordia in a five week human embryo from the
ventral aspect. The pancreas arises from dorsal and ventral regions of
the foregut endoderm, and the liver arises from the ventral endoderm adjacent
to the pancreas endoderm.
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3) FGFs play an important role in the development and proliferation
of both hepatic and pancreas cells. FGF10 maintains the proliferation
of early pancreatic cells (2), and FGFs from
cardiac mesoderm induce the formation of liver in the adjacent endodermal
cells (14). In vitro research has proven that
the pancreas is the default morphology for both of these endodermal derivatives
and that liver develops only under the influence of signaling molecules
from cardiac mesoderm. Endoderm in close contact with cardiac mesoderm
excludes the development of the pancreas (9).
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