Topic 13

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BIOL 370 – Developmental Biology
Topic #13
Neural Crest Cells and Axonal Specificity
Lange
In this chapter, we continue to look at more advanced development of the
ectoderm. The foci we shall have in this chapter, however, will examine how the
ectoderm will be further developed specifically in the
• NEURAL CREST CELLS
• AXONAL SPECIFICITY
Within each of the above, we will specifically examine:
• Formation of the facial skeleton, pigment cells, and the peripheral nervous
system using neural crest cells
• Formation of axonal growth cones
The key underlying concept with this chapter is to recognize how progression in
development of the neural crest cells and the axonal growth cones both require
the cells to significantly migrate for successful development. We shall be
examining some of the chemical signals that help guide these processes.
Figure 10.1 Neural crest cell migration (Part 2)
NOTICE THE SMALL SIZE OF THE NEURAL CREST CELLS
Experiment 1 & 2 are the same
experiment in two different trials.
flourscent dextran was injected into the
neural crest cells and their movement
during development followed.
Figure 10.2 Model for neural crest lineage segregation and the heterogeneity of neural crest cells
Four types of cells are in the
neural crest zone (all are
committed cells, but are
progenitors):
•
•
•
•
C = cartilage/bone
G = glia
N = neurons
M = melanocytes
Figure 10.4 Regions of the chick neural crest
•
Cranial portion of neural crest 
bones & cartilage of face and neck,
cranial nerves
•
Cardiac portion of neural crest 
differentiates and divides pulmonary
arteries and aorta
•
Vagal & Sacral portions of neural
crest  form parasympathetic
nervous system of the digestive
system
•
Trunk portions of the neural crest 
sympathetic neurons, melanocytes,
and adrenal medula.
Cranial portion of neural crest bones & cartilage of face and neck, cranial nerves
Figure 10.12 During craniofacial development, mesencephalic cranial neural crest cells migrate to
become the mesenchyme of the future face and much of the skull
Figure 10.17 The influence of mesoderm and ectoderm on the axial identity of cranial neural crest
cells and the role of Hoxa2 in regulating second-arch morphogenesis
Cardiac portion of neural crest differentiates and divides pulmonary arteries and aorta
Figure 10.15 The septum that separates the truncus arteriosus into the pulmonary artery and the
aorta forms from cells of the cardiac neural crest
The appearance of the
“normal” human heart
in section.
Ventral Septal Defect - the
most common congenital
cardiac anomalies.
• Found in 30-60% of all
newborns with a
congenital heart defect
• This equates to about 2-6
per 1000 births.
• During heart formation,
when the heart begins as a
hollow tube, it begins to
partition, forming septa.
Patent Ductus Arteriosus
Prior to parturition, a blood vessel
called the ductus arteriosus connects the
pulmonary artery — the artery carrying
blood to your lungs — and the aorta, the
large artery that carries blood away from
the heart. In mammals, prior to
parturition, the ductus arteriosus allows
blood to bypass the lungs because the
embryo receives oxygen through the
placenta and umbilical cord.
Transposition of the Great Arteries
With this defect, the positions of
the and the pulmonary artery, are
reversed (transposed). Due to this
transposition of the great arteries,
the aorta arises from the right
ventricle instead of the left
ventricle and the pulmonary artery
arises from the left ventricle
instead of the right. This prevents
nourishing oxygenated blood from
reaching the body.
Vagal & Sacral portions of neural crest form parasympathetic nervous system
of the digestive system
Parasympathetic
Sympathetic
Eye
Brain stem
Salivary
glands
Heart
Eye
Skin*
Cranial
Sympathetic
ganglia
Salivary
glands
Cervical
Lungs
Lungs
T1
Heart
Stomach
Thoracic
Stomach
Pancreas
Pancreas
Liver
and gallbladder
L1
Liver and
gallbladder
Adrenal
gland
Lumbar
Bladder
Bladder
Genitals
Genitals
Human Anatomy and Physiology, 7e
by Elaine Marieb & Katja Hoehn
Sacral
Copyright © 2007 Pearson Education, Inc.,
publishing as Benjamin Cummings.
Trunk portions of the neural crest  sympathetic neurons, melanocytes,
and adrenal medula
Figure 10.5 Neural crest cell migration in the trunk of the chick embryo
Neural crest cell movement shown
in the dark, teal blue layers.
Figure 10.6 All migrating neural crest cells are stained red by antibody to HNK-1
(Also, see
Lipinski et. al., 1983)
Figure 10.8 Entry of neural crest cells into the gut and adrenal gland
In “A” the fluorescence is
highlighting enteric ganglia that
control peristaltic movement
In “B” the solid circle represents
the adrenal medulla, the green
fluorescence
Two different stainings are seen in
“A”.
The neural crest cells are migrating
into the adrenal as seen by the red
stained cells for Sox8. The green
stain (SF1) identifies adrenal cortex
cells.
Figure 10.9 Neural crest cell migration in the dorsolateral pathway through the skin
In this mouse image (A), the
purple is staining melanoblasts.
In the chick (B), the arrows point
to melanoblasts
Melanoblasts will of course
create melanocytes.
Figure 10.10 Cranial neural crest cell migration in the mammalian head (Part 1)
Pharyngeal Arches are early
regions that develop into a
multitude of structures.
Figure 10.10 Cranial neural crest cell migration in the mammalian head (Part 3)
Figure 10.11 Intramembranous ossification
Below, we see the chick head
as bone formation
(ossification of cartilage)
occurs.
Figure 10.28 The trigeminal ganglion has three main branches
Trigeminal Ganglia branches into:
•
Ophthalmic nerve
•
Maxillary nerve
•
Mandibular nerve
Bone Morphogenetic Protein 4
The growth of these nerve branches is
governed by the BMP4 gene.
Figure 10.29 Embryonic axon from a rat dorsal root ganglion turning in response to a source of
NT3
Neurotrophin 3
NT3 is a neurotrophic factor in
the nerve growth factor family
(NGF) family of neurotrophins.
It is a protein growth factor
which has activity on certain
neurons in the nervous system
In the images, we see how
NT3 added to the region near
rat dorsal root ganglion causes
turning of the growing axon
cones towards the chemical.
Figure 10.30 Differentiation of a motor neuron synapse with a muscle in mammals
An example of growth cones
being used to differentiate a
neuromuscular junction.
Figure 10.31 Effects of NGF and BDNF on axonal outgrowths
Nerve Growth Factor (NGF) and Brain-Derived Neurotrophic Factor
(BDNF) are both neurotropins, but their effects are specialized.
NGF effect pronounced
BDNF effect minimal
NGF effect pronounced
BDNF effect pronounced
NGF effect minimal
BDNF effect pronounced
Figure 10.32 Making a “brainbow”
• A brainbow is a construct in which
neuroanatomists can process and define
individual neurons in the brain from
neighboring neurons using a wide hue of
fluorescent proteins.
• Random expression of different ratios of red,
green, and blue derivatives, it is possible to
flag each neuron with a distinctive color.
• This process has been a major contribution to
the field of connectomics, or the study of
neural connections in the brain.
• The study of neural pathways is also known as
hodology by earlier neuroanatomists.
Jeff W. Lichtman
Joshua R. Sanes
The technique behind creating a “brainbow” was originally
developed in the Spring of 2007 by a team led by Jeff W.
Lichtman and Joshua R. Sanes.
End.
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