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Neuroscience

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Midbrain Differentiation: Isthmic Organizer

NEURO-YHIBRJ

In embryology, an organizer is a group of cells that acts upon surrounding cells and tissues forcing them to adopt particular fates. In the developing brain, one such organizer is found at the boundary of midbrain and hindbrain, also known as isthmic region, and is called isthmic organizer. Morphogenetic molecule Fgf8 is produced by the isthmic organizer and transforms fates of the neighboring neuroepithelium into tectum arising from midbrain and cerebellum arising from hindbrain.

Which classic embryologic studies supported such role for an isthmic organizer in midbrain and hindbrain development? Select ALL that apply.

A

Transplantation of a piece of diencephalon next to isthmic organizer caused it to differentiate into tectum.

B

Beads soaked in Fgf8 and transplanted into developing diencephalon caused it to differentiate into tectum.

C

Transplantation of a piece of diencephalon in the midbrain, but close to midbrain/diencephalon boundary and away from isthmic organizer did not change its fate.

D

Transplantation of isthmic organizer into rhombomeres 2-4 instructed them to develop into cerebellum.