neural crest - university of minnesota duluthpschoff/documents/neuralcrest_000.pdf · neural crest...
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Neural Crest Overview
Neural crest derivatives
NC cell specification and migration
NC regions
Trunk
Vagal
Cardiac
Cranial
Neural Crest Derivatives
T. Halliday, 1980
Lora Bryson
Styracosaurus albertensis
© Franco Andreone
J. Briscoe
Michael Sereda, M. D.
Neural Crest Cells
Neurons, Schwann cells, pigment cells
Initiation – interactions between neural plate and presumptive epidermis NC undergos epithelialtomesenchymal transformation
stimulated by Wnts, BMPs, FGFs
Neural Crest Migration
S.J Kimber
Migration pathways are controlled by extracellular matrices and by chemotactic factors permissive and instructive signals negative signals also
Soluble factors also control migration of certain NC cell populations; e.g. glialderived neurotrophic factor produced by the gut mesenchyme attracts vagal and sacral NC cells
Neural Crest Regions forebrain
Vagal Cardiac
Trunk
Sacral
hindbrain midbrain
Cranial
(named after the vagus nerve – innervates the heart)
Trunk Neural Crest
Ventrolateral
forebrain
Vagal
hindbrain midbrain
Sacral
Ventrolateral – early migration; into and through the anterior (not posterior) half of each somite
cells that travel through the somite form sympathetic ganglia, adrenal medulla, aortic nerve clusters
cells that remain in the somite = dorsal root ganglia (sensory neurons)
Two migration pathways:
somite
Trunk Neural Crest
Ventrolateral
Dorsolateral
forebrain
Vagal
hindbrain midbrain
Sacral
Dorsolateral – later migration; travel between ectoderm and somite mesoderm; later move into epidermis form melanocytes
Ventrolateral – early migration; into and through the anterior (not posterior) half of each somite
Two migration pathways:
Vagal and sacral neural crest cells generate the parasympathetic (enteric) ganglia of the gut
Vagal and Sacral Neural Crest forebrain
Cardiac
hindbrain midbrain
Cranial
Trunk
Cranial (cephalic) neural crest cells form craniofacial mesenchyme; creates (among others) facial cartilage and bone cranial neurons glia connective tissue
Cranial Neural Crest
Cranial NC cells also enter pharyngeal arches and pouches; form thymic cells odontoblasts of tooth primordia bones of the middle ear and jaw
forebrain
hindbrain midbrain
Cranial
Cranial NC Migration into Pharyngeal Arches
Neural crest cell migrate into pharyngeal arches
Human embryo 31 d
Pharyngeal arches
12
3
4
Mammalian Facial Development
upper and lower jaws
Nasal placode
Stomodeum
NC cells contribute: skeletal elements (face, hyoid, etc.) cartilage elements (e.g. in trachea) inner ear bones cranial nerves (V, VII, IX, X,)
Bone – Intramembranous Ossification NCderived mesenchyme condenses into nodules some become osteoblasts – secrete collagenproteoglycan osteoid matrix – binds calcium
osteocytes – osteoblasts that become embedded in the bony matrix periosteum – membrane surrounding bones
Osteoblasts Osteocytes
Bone spicule – calcifiction
Cranial NC cells form facial skeleton:
Cardiac Neural Crest Cells The heart forms in the neck region, just below the pharyngeal arches
Cardiac NC cells form the endothelial lining of the aortic arches also forms the septum between the aorta and pulmonary artery; divides the truncus arteriosus