Chapter 14 the Neural Crest

8/8/2019 Chapter 14 the Neural Crest

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Joson, Angelo Eleno F.

4BIO 6



Neural Crest

Labeled as thefourth germ lay er

Gives rise tonumerous structuresin both cranial and

caudal parts of anembr y o



Evolution of Neural

Crest

Homologous to protochordatedorsal midline epidermis

Emergence of new cell properties:

1. Pluripotenc y

2. Delamination-migration

3. Anteroposterior positional

v alue4. Complex craniof acial structure



Controlling Genes

Protochordates:

BMP Factors

- Transforming Growth Factor

(TGF-)-BMP4 and BMP7

Vertebrates

- Neuropilin 1

- Sox10

- Sema3a

N-cadherin

rhoB



Markers for Tracing

Slug/Snail

-Zinc finger genes

-Induction and subsequent

migration

-R adioactive isotopes

--staining antibodies

- (NC-1, HNK-1)

-- lipophilic d y es (DiI)



Origins of the

Neural Crest Cells Arise from neural tube

From dorsal midline

Emergence occur from anterior to

posterior parts of embr y o

Pinch off from neural epithelium just as the neural tube forms

Emerge as mesench y mal cells

(Mour y and Jacobson) Experimenton axolotls: NCCs form at borderbetween neural plate andepidermis



Origins of the

Neural Crest(Scherson and associates)Experiment on chick embr y os:NCCs can form in other parts of neural tube aside from the dorsalside

Upon formation, the y lose celladhesion molecules

- N-CAM

- N-cadherin

Levels of fibronectin and othersurf ace matrix molecules rise



Migration of Neural Crest Cells

NCCs loseN-cadherinand becomestimulatedto migrate

NCCs lea ve the

neural tubearea

NCCs enter a cell-free zonedispersed withextracellularmatrix

Gene f actorsf acilitatemigration

Interact withtissues andbecomelocalized to formspecializedstructures






Migration of Neural Crest Cellsy Influences of extracellular matrix

y Laminin

y Fibronectiny T y pe IV collagen

y Chondroitin sulf ate

y H yaluronic Acid

y Heparan Sulf atey Integrins






Loo Aka Chu, Charisa Camille C.

4 Bio - 6



Differences in premigratory neural crest cells:

1. Not all shows the same staining properties whenexposed to monoclonal antibodies or

histochemical reagents

2. Single neural crest cells do not all produce the

same types of differentiated progeny

3. When pieces of neural tube are grafted intodifferent craniocaudal levels, some neural crest

derivatives do not form.





1. Embryonic tissues

2. Envir onment



Cranial Crest Trunk Crest

Nervous System:Sensory Nervous

System

Ganglia:

(V) Trigeminal nerve

(VII) Facial nerve (root)

(IX) Glossopharyngeal (Superior

ganglion)

(X) Vagus nerve (Jugular ganglion)

Spinal ganglia

Rohon-beard cells (amphibian

larvae)

Autonomic Nervous

System

Parasympathet ic ganglia:

Ciliary

Ethmoidal

Sphenopalat ine

SubmandibularVisceral

Parasympathet ic ganglia:

Pelvic plexus

Remaks (birds)

Visceral

Sympathet ic ganglia:

Superior cervical

Paravert ebral

Prevert ebral



Cranial Crest Trunk Crest

Noneural cells Oligodendroglia

Sat elit e cells of sensory ganglia

Schwann cells of peripheralnerves

Neuromasts

Sat elit e cells of ganglia

Schwann cells of peripheral

nervesNeuromasts (f ish lat eral lines)

Pigment cells Melanopores

Xanthopores

Erythrophores

Iridophores

Melanopores

Xanthopores

Erythrophores

Iridophores

Endocrine and

Paraendocrine

cells

Calcitonin-producing cells

Carot id body

Parafollicular cells (Thyroid)

Adrenal medulla

Neurosecretory cells of heart

and lungs

Mesectodermal

cells

Skeleton

Cranial vault

Nasal and orbit al

Ot ic capsule

Palat e and maxillary

Sphenoid

Trabeculae

Visceral cart ilages





Neural crest Derivative Interacting Structure

Bones of Cranial Vault Brain

Bones of base of skull Notochord, brain

Pharyngeal ar ch car tilages Pharyngeal endoderm

Meckel·s Car tilage Cranial ectoderm

Maxillary bone Maxillary ectoderm

Mandible Mandibular ectoderm

Palate Palatal ectoderm

Otic capsule Otic vesicle

Dentine of teeth Oral ectoderm

Glandular str oma: thyr oid,

parathyr oid, thymus, salivary

Local epithelium

Adr enal medullary chr omatin cells Glucocor ticoids secr eted by adr enal cor te x

Enter ic neur ons Gut wall

Sympathetic neur ons Spinal cord, notochord, somites

Sensory neur ons Per ipheral tar get tissue

Pigment cells Extracellular matr i x along pathway of

migration





Trunk Neural Crest Cells extends from the caudal part of the embryo until

the 6th somite

cells disperse after neural tube closes multipotent cells

3 major pathways: dorsolateral , ventral &ventromedial



Neural Crest Migration

In Mammals, melanocytes

distribute pigment granules to

basal ectodermal cells

In lower vertebrates, pigment

cells remain underneath the

ectoderm

Dorsolateral

Between dorsal

ectoderm &

somites

Pigment Cells or

Melanocytes



Somite and dorsal

aorta

Ventral route

Between somites

and neural tube

Ventromedial

Paired spinal

ganglia

Sympathoadrenal

lineage

Sympathetic Nervous

System &

Adrenal Medulla





Sympathoadrenal lineage

Gives rise to bipotential progenitor cells -->

sympathetic neurons ( FGF / F ibroblast

Growth

F actor ) and chromaffin cells

Future adrenal gland

Chromaffin cells : gland-like cells active in

forming neurotransmitters; reacts withchromic acid salts

adrenal medulla





Gershon & associates (1993) - moreneurons are present in the gut than in the

spinal cord.

Shift-level transplantation experiments

Gut releases a short-range diffusible factor

proliferate neural crest or neuroepithelial

cells







Hoxb gene complex Hoxb-2, 3 and 4 gene products first

expressed in neural tube

Expression of same Hox genes;

interaction between ectoderm and neural

crest cells in branchial arches





Cranial neural crest cells are

imprinted with morphogenetic

instruction that could relate to

their level of origin.

Wider assortment of cell

types

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Chapter 14 the Neural Crest