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To determine the
mechanism of
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duct formation
Herzlinger
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introduced a
lineage marker into
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different sites
of the
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intermediate
mesoderm.
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Lineage
marker is 1. a label
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that is
maintained by the
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progeny of a
cell, no mater what
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they become ie
not subject to
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variation in
gene expression. 2.
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does not spread
from cell to cell.
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She found that a
stream of
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labeled cells
appeared within 24
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hours of marking
one spot at
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s10. This stream
was the
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nephric duct-we
see it in cross
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section.
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This experiment
indicates that
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migration is
involved but its too
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fast for cell
replication to be the
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driving force.
Also it shows that
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cells are not
being incorporated
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from an external
source,
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because otherwise
it would
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appear as a
mosaic.
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