Introduction
The neural crest are bilaterally paired strips of cells arising in the ectoderm at
the margins of the neural tube. These cells migrate to many different locations
and differentiate into many cell types within the embryo. This means that many
different systems (neural, skin, heart, endocrine, GIT) will have a
contribution fron the neural crest cells. General neural development is also covered
in another section of these notes (Neural).
Beside the spinal cord neural crest cells form the sensory ganglia (dorsal
root ganglia). In the head region neural crest cells migrate into the pharyngeal
arches (as shown in movie below) and form many different structures.
Developmental Overview
Neural Crest Origin
- lateral region of neural plate
- dorsal neural fold->tube
Neural Crest Origin
- 2 main regions
- head (CNS)
- differentiate slightly earlier
- mesencephalic region of neural folds
- body (spinal cord)
- lateral edges of fused neural tube
Neural Crest- Generation 1
- Chicken Studies
- Bronner-Fraser M PNAS 1996 Sep
3;93(18):9352-7
- demonstrate that they are not a segregated
population
- Interactions between the neural plate and
epidermis can generate neural crest cells, since
juxtaposition of these tissues at early stages
results in the formation of neural crest cells
at the interface.
- At cranial levels, neuroepithelial cells
can regulate to generate neural crest cells
when the endogenous neural folds are removed,
probably via interaction of the remaining
neural tube with the epidermis.
- progenitor cells in the neural folds are
multipotent, having the ability to form
multiple ectodermal derivatives, including
epidermal, neural crest, and neural tube
cells the neural crest is an induced
population that arises by interactions
between the neural plate and the
epidermis;
- the competence of theneural plate to
respond to inductive interactions changes as
a function of embryonic age.
Neural Crest- Generation 2
- At cranial levels, neuroepithelial cells can
regulate to generate neural crest cells when the
endogenous neural folds are removed, probably
via interaction of the remaining neural tube
with the epidermis.
- progenitor cells in the neural folds are
multipotent, having the ability to form multiple
ectodermal derivatives, including epidermal,
neural crest, and neural tube cells
- the neural crest is an induced population
that arises by interactions between the neural
plate and the epidermis;
- the competence of theneural plate to respond
to inductive interactions changes as a function
of embryonic age.
Neural Crest Derivatives
- migrate throughout the embryo and give rise
to many different cells
- see table in class notes
- ganglia
- cranial, dorsal root, sympathetic trunk
- celiac, renal, plexus in GIT
- glia, schwann cells
- melanocytes (skin)
- adrenal medulla (chromaffin cells)
Neural Crest-Differentiation
- Begins in cranial region when still neural
fold
- In spinal cord from d 22 until d26
- after closure of caudal neuropore
- rostro-caudal gradient of
differentiation
Neural Crest-Head (see also Head
Development Notes)
mesencephalon and caudal proencephalon
- parasympathetic ganglia CN III
- connective tissue around eye and nerve
- head mesenchyme
- pia and arachnoid mater
- dura from mesoderm
Neural Crest-Head
mesencephalon and rhombencephalon
- pharayngeal arches
- look at practical notes on neck and
head.
- cartilage rudiments (nose, face, middle
ear)
- face
- dermis, smooth muscle and fat
- odontoblasts of developing teeth
Neural Crest-Head
rhombencephalon
- C cells of thyroid
- cranial nerve ganglia
- neurons and glia
- parasympathetic of VII, IX, X
- sensory ganglia of V, VII, VIII, IX, X
Neural Crest- Spinal Cord
- peripheral nervous system
- dorsal root ganglia (sensory N)
- parasympathetic ganglia
- sympathetic ganglia
- motoneurons in both ganglia
- all associated glia
Neural Crest- Migration
- Larsen- Chapter 5 p 107
- LeDouarin 80's
- Development of the peripheral Nervous system
from the neural crest
- Ann Rev Cell Biol 4 p375
- transplantation experiments in
chicken/quail
- nucleoli to differentiate different
species
- can follow path of migration of
transplanted cells
- now molecularly tag neural crest cells
(LacZ)
Neural Crest- Migration 1
- Living Zebrafish Studies
- (Jesuthasan Development 1996
Jan;122(1):381-9
- Neural crest cells in the trunk of
vertebrate embryos have a choice of pathways
after emigrating from the neural tube: they
can migrate in either the medial pathway
between somites and neural tube, or the
lateral pathway between somites and
epidermis.
- In zebrafish embryos, the first cells to
migrate all choose the medial pathway.
- High resolution imaging of cells in
living embryos suggests that neuralcrest
cells do so because of repulsion by somites:
cells take the medial pathway because the
lateral somite surface triggers a paralysis
and retraction of protrusions (contact
inhibition or collapse) when the medial
surface does not.
- Partial deletion of somites, using the
spadetail mutation allows precocious entry
into the lateral pathway, but only where
somites are absent, supporting the notion
that an inhibitory cue on somites delays
entry.
Neural Crest- Migration 2
- Primates
- N-CAM labelling of cranial neural crest
cells (Peterson, Anatomy & Embryology 1996
Sep;194(3):235-46
- At stage 10 (8-11 somites), crest
emigration occurred in areas of unfused
neural folds through focal disruptions in the
neuroepithelial basement membrane in both the
rostral and pre-otic regions, although there
was little evidence of crest migration in the
post-otic hindbrain. By stage 11 (16-17
somites), the neural folds were fused (pre-
and post-otic hindbrain) or in the process of
fusing (rostral hindbrain), yet crest cell
emigration was apparent in all three areas
through discontinuities in the basement
membrane. Emigration was essentially complete
at stage 12 (21 somites) as indicated by
nearly continuous cranial neural tube
basement membranes. At this stage the
pre-ganglia (trigeminal, facioacoustic and
glossopharyngeal) were consistently stained
with N-CAM.
Use cell surface markers and ECM adhesive
proteins
- laminin and collagen-IV in neuroepithelial
basement membranes
- Neural Crest- Migration
- Neural crest cells migrate
- + on specific adhesive pathways
- laminin
Differential neural crest cell attachment and
migration on avian laminin isoforms.
- Isolated neural crest cells differentially
attached and migrated on these laminin isoforms,
showing a clear preference for Laminin-G
(gizzard tissue) over Laminin-alpha x (heart
tissue).
- fibronectin
- T-cadherin (truncated cadherin, Ca dependent
adhesion molecules)
ECM inhibitor pathways
- Aggrecans and PG-M/versicans represent two
newly defined families of hyaluronan-binding
proteoglycans
- S103L chondroitin sulfate proteoglycan.
Other Factors
- High glucose concentration inhibits
migration of rat cranial neural crest cells in
vitro.
- may explain some teratogenic effects of
diabetic pregnancy
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Comments
This Page is under Development (completed when this text removed).
Neural crest cells contribute to many different tissues and systems throughout the entire embryo.
While the cells originate from the ectoderm layer, unlike the neural tube which "pinches off" from the surface ectoderm,
the neural crest cells head off on migrations throughout the embryo forming a diverse range of cell types and contributions to different tissues.
This behaviour also means that failure of correct migration or differentiation can lead to a number of different abnormalities.
Please email Dr Mark Hill if you wish to make a comment about this current project.
Some Recent Findings
