Patterning Of NS Flashcards
Patterning depends on signals from ___________
Examples
Organiser regions
Secondary organisers:
Anterior neural ridge
Zone limitans
Isthmic organiser
AP patterning has two main steps:
1) coarse grained patterning: subdivides major regions
2) Fine-grained patterning: Worthing individual regions (eg hindbrain)
In the frog _______ stage, ________ cells lie below the forming neural _______ and send activation signals (____________) to ensure cells become _________.
Transformation signal (______, ____, ______) from caudal end gives _______ patterning
Gastrula Mesoderm Plate BMP inhibitors Neural
Wnt
RA
FGF
Posterior
The hindbrain is ________ into __________.
The boundaries between these are important because ___________.
__________ differentiate segmentally in the hindbrain.
Trigeminal in _____ and facial in ______
Cells are _______ to ________
Segmented
Rhombomeres
Axon tracts
Motor neurons
R3
R4 and R5
Restricted
One rhombomere
The ______ organiser produces ________ which diffuses out and patterns __________
This is involved in setting expression boundaries of __________
Isthmic organiser
FGF8
Rosteral rhombomeres
Hox genes
Mutations in SHH in humans cause
Holoprosencephaly
Single brain ventricle
Facial dysmorphisms
Cyclopia
AP systems depend on
Localised RNA and/or protein products, maternally encoded and localised in the egg during oogenesis
Terminal and DV systems…
Don’t depend on localised products inside the egg
Mediated by localised signals outside the egg (synthesised by follicle cells) that are transmitted by receptors in the egg membrane
4 maternal patterning systems
Posterior- nanos
Anterior- bicoid
Terminal- torso
Dorsoventral-till
Morphogen
Any substance active in pattern formation whose spatial concentration varies and to which cells respond differently at different threshold concentrations
Gap genes are able to
Cross regulate each other
Gene regulatory network
Parasegment
Primary boundary in the embryo
Cells will not cross during development
_______ expression is activated by high levels of _____ or _____
After cellularisation, ________ activate __________ and ___________ in adjacent cells
_________ induces expression of __________
_________ and __________ are secreted and activate a signalling cascade that reinforces ________ and _________ expression
A ___________ mechanism
Engrailed
Eve or Ftz
Pair rule Wingless Engrailed Engrailed Hedgehog Wingless Hedgehog Engrailed and hedgehog
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