Week 5 Objective 2 Flashcards
Tripartite brain
prosencephalon
msencephalon
rhombencephalon
Presencephalon is also known as
neuromere = prosomeres
prosencephalon gives way to the telenchephalon and diencephalon
Mesencephalon
gives way to mesencephalon
Rhombencephalon gives way to
rhombomeres
Metencephalon
Myelencephalon
how many rhombomeres in the hindbrain of the human
7
Tripartie brain established through what signaling molecule
Wnt-8 gradient
Prosencephalon expresses what transcription factors?
Otx-2, future forebrain and (?) midbrain
Mesencephalon expresses what transcription factors?
Otx-2
rhombencephalon expresses
Gbx-1 transcription factor, future hindbrain and spinal chord
Neural tube segmentation: 3 organizing centers
Isthmic organizer, anterior neural ridge, zona limitans
Isthmic organizer
segmentation organizer
important in organizing midbrain and cerebellum
driven by wnt-1 and FGF-8
Anterior neural ridge
organizes
telencephalon, diencephalon, pituitary gland, olfactory area
driven by Shh and FGF-8
Zona limitans
organizers border between dorsal and ventral thalamus
drive by Shh
Segmentation Genes in the hind brain
r3 and r5 are established via signaling molecule
knox 20
r5 has half a dozen signaling molecules to organize its segment. what are they?
knox 20 and [kreisler and hoxa-1] , retinoic acid
retinoic acid gradient establishes
r4-r-7
Hox gene expression
patterning, segmentation
determines cranial nerves and pharyngeal arch derivatives
retinoic acid gradient stimulates expression of
hoxa-1 and hoxb-2
Why are caudalmost cells on the neural plate considered stem cells?
They’re undifferentiated and will go on to create neurons and the spinal column
FGF-8
expressed by paraxial mesoderm: stimulates caudal neural plate cells to proliferate, but not differentiate
its retinoic acid that causes the differentiation
FGF-8 causes
retinoic acid causes
FGF-8 causes proliferation (released by paraxial mesoderm)
retinoic acid causes differentation (released by somites)
Why is neural crest tissue sometimes considered to be a fourth germ layer?
As neural tube is closing and separating from ectoderm, cells leave the tube and migrate to different places becoming many different structures
What are sensory placodes?
ectodermal thickenings: cells from placodes and neural crest interact closely to form sensory ganglia of cranial nerves (V, VII, IX, and X)
Where do the placodes come from?
from horseshoe shaped preplacodal domain around the anterior neural plate established during gastrulation
