page_title: Cyclopamine
section_title: Embryological
hierarchical_section_title: Cyclopamine / Embryological
caption_attribution_description: English: Cyclopamine causes an extreme degree of holoprosencephaly as depicted. Information gathered from [1].
context_page_description: Cyclopamine is a naturally occurring chemical that belongs in the family of steroidal alkaloids. It is a teratogen isolated from the corn lily that causes fatal birth defects. It prevents the embryonic brain from separating into two lobes, which in turn causes the development of a single eye. The chemical was named after this effect, as it was originally noted by Idaho lamb farmers who contacted the US Department of Agriculture after their herds gave birth to cycloptic lambs in 1957. It then took more than a decade to identify the corn lily as the culprit. Later work suggested that different rain patterns caused the sheep to graze differently, impacting the amount of corn lily ingested by pregnant sheep. The poison interrupts the sonic hedgehog signaling pathway during development, thus causing birth defects.
context_section_description: Cyclopamine causes the most advanced form of holoprosencephaly. Because it blocks Shh signaling, the embryonic brain no longer divides into lobes (becomes alobar). Thus, only one optical track develops, hence the cycloptic (singular) eye. Furthermore, this disease is fatal and presently has no cure. 
   One can imagine one half of the healthy brain not dividing, but instead growing out and resembling the alobar brain.  This occurs in cases of cyclopamine poisoning. This malformation is always fatal, and it is worth noting that there are lesser cases of holoprosencephaly that aren't always fatal. However, embryonic cyclopamine poisoning causes the most extreme and therefore fatal cases.
caption: In this figure, the healthy brain has two lobes whereas the severe state of holoprosencephaly is alobar (has no lobes).
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