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left-right axis patterning is very hard to detect in the
embryos. Perhaps by staining regions of the embryo we would
have been able to see the direction of the heart loop and
treated our embryos too early to see problems with
truncation. Had we treated an additional set a later
developmental stage we may have been able to see truncation
in the embryos as a result of the cyclopamine.
clearly affected the development of the eyes. From this we
conclude that sonic hedgehog is in fact a key player in the
development of the eye in Medaka fish. This is in agreement
with the model that has been developed for the role of SHH
in eye formation in other vertebrates (Chiang et al., 1996).
The model suggests that there is an optical field anywhere
on which the eye cups can form. SHH is thought to be
involved with the separation of this field into two distinct
optical regions. By blocking the SHH signal one
blocks this separation of the optical field. Depending on
the degree to which the signal is block determines the
degree to which the eyes are separated. This is why in some
cases we saw full cyclopia and others only had fused eyes.
This model however, does not account for the detached lenses
seen in many of the embryos.
there was no statistical significance between the control
and treated embryos with circulatory defects we could not
conclude that the cyclopamine was the agent affecting its
formation. There were a lot of the control embryos with the
same defect. For this reason we concluded that the
circulatory defects were most likely do to the ethanol and
not the cyclopamine. If we had more time to further
Last Modified: 5 May 2000