BIO380H5 Lecture Notes - Lecture 9: Fgf8, Mesen, Sonic Hedgehog

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9 Jun 2016
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Closure of neural tube occurs in the region where the earliest somites appear then spreads cranially and caudally leaving the cranial and caudal neuropores @ 24 days gestation and 26 days respectively. Local fgf-8 together with shh secreted from anterior neural ridge will influence development of telencephalon. Zona limitans is under the influence of prechordal mesoderm. Early in development there"s isthmic organizer which will separate the forebrain and midbrain (telen dien and mesen) from hindbrain (rhomben) and produce otx2 and gbx2. Isthmic organizer under influence of wnt and fgf8. Anterior visceral endoderm and prechordal plate influence neural tube to tell it which part should be anterior and posterior. Fgf-8 will be expressed by the part posterior to isthmic organizer. Whenever expressing wnt = you are the future midbrain. Notochord is influencing almost the whole area from mesencephalon to very end of spinal cord. Shh from zona limitans will enhance development of diencephalon.